[gavronm]

Hey Gang:

On [[March]] May 16 and 17 I participated in the 2-day BMW CCA Windy City chapter HPDE at Autobahn Country Club in Joliet, IL. This was my first HPDE in my 2011 335d m-sport and I thought I'd share some thoughts and observations in case anyone else is thinking about taking their D to the track (short answer: You should!). I'm going to try to discuss everything I wondered about before the event and hopefully this post and resulting thread will prove to be a helpful resource for anyone with similar aspirations.

TL;DR – My 2011 335d m-sport with 58K miles was more than suitable for 2 consecutive days of hard track driving. The car was stock except for Motul RBF 600 brake fluid and a set of EBC Yellowstuff pads that I installed just before the event. In hindsight I wish I’d have used a more race-specific pad. Speed wise I was in the top 3rd or so of the intermediate group and only experienced very modest brake fade, so if you’re a Novice or just moving into the Intermediate group you will probably be fine with yellowstuff or even OEM pads – but absolutely upgrade your brake fluid.
E46 and later M3s could gradually pull away from me on the long straights but I was slightly faster than the E36 M3s. I was very evenly matched with other e9X 335s. All of this is completely anecdotal of course because I have no idea of the mods or mileage that might have been on those other cars and driver skill will make a huge difference in whether one car is able to catch another down a straight regardless of which car has better straight-line acceleration.

My stock-size Continental Extremecontact DW tires did an adequate job in the dry and were spectacular in the wet. Only thing I regret is not going with 245/35/18 fronts when I replaced the tires a few months back because, unsurprisingly, when traction got sketchy it was always on the understeer side of things.

When understeer is kept in check, the car handles magnificently. Very neutral through the corners and responsive to driver input. The most enjoyable skill I acquired over the weekend was the ability to adjust my line through certain corners with nothing but throttle modulation.

One surprise was how difficult it was to find the proper shift pattern. The car is so quiet and shifts are so smooth it’s very hard to know what the transmission is doing. It was only after I had my instructor watch the shift indicator and call out the gears for me that I was able to get everything squared away. Keep it between 2K and 3.5K coming out of the corners and you’re good to go. I ran most of the track in 4th with only two spots requiring a downshift to 3rd.

I learned a TON and love my car more now than I did two weeks ago. It’s great to know exactly where the limits are and what it feels like as those limits are approached. I’m a safer, better driver. Don’t for a second hesitate to take this car to the track. Yes it’s a sedan, yes it’s a diesel, yes it’s an automatic, but it is still the Ultimate Driving Machine.

On to the details…

THE DRIVER - The vast majority of my track time before this was on motorcycles and in shifter carts. I hadn't driven a full sized car on a track at speed for many years, but because I knew the fundamentals from my time on bikes and carts and was generally among the faster students in those vehicles I was put in the Intermediate group, which turned out to be exactly the right place.

THE CAR - 2011 335d m-sport, bone stock, 58K miles on OEM 18" style 162 with Continental ExtremeContact DW 225/40/18 front and 255/35/18 rear. As mentioned above I debated getting 245s up front when I bought the tires and really wish I had as I was getting a lot more understeer than oversteer throughout the day.

CAR PREP - Removed anything that wasn’t bolted down, checked all fluids, replaced brake fluid with Motul RBF 600, installed EBC Yellowstuff pads on all corners, and that's it mechanically. I installed an adhesive GoPro mount on the interior light cluster just behind the moon roof (check with your organizer to see if this is allowed). Once to the event I installed the tow hook onto the front bumper – just in case, and removed the E60 jack kit and spare tire that I normally keep in my trunk.

Not exactly "car prep" but I also purchased $25,000 worth of event insurance with a BMW CCA discount for about $180 from Lockton Motorsports - good for the entire weekend. For me anyway the peace of mind was worth every penny.

DRIVER PREP – Started packing and prepping the week before the event. Packed a large Rubbermaid container with the tools required to change and properly re-torque wheels and brake pads. Also packed a tarp, mechanic gloves, rain jacket, spare set of brake pads (the OEM pads I had removed, which were still decent), extra brake fluid, brakeclean, rags, granola bars, a 1ft square piece of plywood to place between the jack and the paddock asphalt, if needed, and a power pack for charging my phone and my GoPro. Also had a cooler with bottled water and some diet cokes (yeah, I know).

I watched every online video of the Autobahn south track I could find multiple times. I didn’t drink all weekend and got as much sleep as possible with a 2 year old and 8-month pregnant wife.

EVENT LOGISTICS - As noted above the two-day event was run by the BMW CCA Windy City chapter. It was very well organized and pre-event communication was terrific. Great checklist and instructions for prepping your car. They arranged for group pre-tech to occur on a Saturday a couple weekends before the event but if you couldn't attend that they provided a checklist to be completed by a mechanic of your choosing.

They had a professional mechanic on hand at the track ready to help out if something did go wrong with your car. Fortunately I never had to pay him a visit but several cars were in and out of the repair barn over the course of the weekend.

There were four student levels – Novice, Intermediate, Expert 1, and Expert 2. Not exactly sure if the expert groups were divided by skill or if was just a result of having a lot of entries at that level. Every novice and intermediate level student was given an instructor and I believe most advanced and some expert level students also had instructors. Instructor matches were made ahead of time and my instructor emailed me about a week beforehand to introduce himself and get some info about me and the car.

I was very impressed with how professionally and safely this event was run. It was good to know that every other car on the track had an instructor on board to keep the driver honest. It can be difficult to organize events with instructors for every student, but if I was at the novice level I would think long and hard before participating in an HPDE that allowed other novice level students on the track without an instructor.

THE DAILY SCHEDULE - There were 4 driving sessions each day - three were 25 minutes and the last one was 20 minutes – a smart way to do it because you’re tired and can start to get sloppy at the end of the day. Each day started at 8:00 with a mandatory safety briefing. Every session was driven with an instructor and you had the option to let your instructor drive the first couple laps of the first session to show you the way around. In between track sessions you had rest and class periods while the other groups also rotated between track, rest, and class. There were two instructor sessions where you could ride with your instructor at speed (highly recommended) and also a lunch time touring session with no passing and a speed limit of 50 mph. Touring proved to be an exceptionally valuable opportunity to go out and search for reference points on the track at a low speed and to practice the perfect line – DON’T WASTE THIS OPPORTUNITY FOR MORE TRACK TIME JUST BECAUSE YOU CAN’T GO FAST! On day 2 a buddy and I went out for touring together and discussed the different reference points and lines we used – my next session out I instantly dropped a full second off my prior times.

CLASS TIME - Our classroom instructor was great and at least at the intermediate level we were able to go a little off script now and then to talk about challenging areas of the track. It was helpful to hear different perspectives from different students and the different tips we were all being given by our different instructors. Autobahn’s in-house instructor put together a really cool turn-by turn breakdown of the track using google maps and onboard footage. It’s too bad they don’t put in on YouTube.

THE TRACK - Autobahn Country Club is basically a country club but instead of a golf course they have a race track. Membership is very expensive (last I heard buy-in was about $25K and annual dues were around $8K) but even that isn't enough to cover all their expenses because they rent out the track for various groups to use. There is a ~1.5 mile north track, ~2 mile south track, and the two can be combined into a single ~3.5 mile track. We were running on the south track while the members ran events on the north track.

The Autobahn south track has 15 turns with a great mix of fast and slow corners, individual corners, and linked corners. Some sections are straightforward, some are very technical. Here's a map of the south track (pdf).

MY GROUP - Other than some X5s that were pulling trailers, I was the only diesel at the event. My run group included M3s of the E36, 46, and 90 variety, several E9X 335s, a well-driven E90 328i m-sport, a very nicely-modded WRX STi, a Cayman S, a GTI, and one hella-impressive 4-door Civic Si that I could only barely pull away from on the straights. As you can tell, even thought this was a BMW event, and BMW was easily the most represented marquee, there was a nice variety of hardware rolling around.

DRIVING IMPRESSIONS

ACCELERATION AND SHIFTING – We all know the d pulls like a freight train at low RPMS. This was both good and bad. The sweet spot coming out of corners was somewhere between 2K and 3.5K RPM. With my stock exhaust, the low revs, and the relatively smooth shifting of the automatic tranny, I couldn’t feel or hear much of anything, which made it very difficult to identify shift points. The DS setting was not able to choose the correct gears so I had to use manual control. It was only after I asked my instructor to call out gear and RPM into and out of corners that I finally was able to consistently be in the same gear on the same turns lap after lap. I needed far fewer shifts than I originally imagined. Unfortunately for me the purchaser of the car did a paddle-shift delete so I was reaching down and yanking the shift lever a few times a lap – not that big a deal, really.

I was somewhat surprised that we ended up leaving full traction control on for the entire weekend. The amazing (or perhaps not amazing) thing is that it only came on when I got something a little wrong. When it did activate it was never intrusive the way it can be when you gas it around a corner from a stand still. Quite frankly if it wasn’t for the blinking indicator light I don’t think I would have noticed it at all. My recommendation, even if you’re running power upgrades, is to leave traction control completely on until it consistently annoys you. Then and only then turn traction control off but leave the DSC on – it may save your bacon. I won’t say it can never happen but based on my experience most people on most tracks in most 335ds will never need to turn DSC off because it is intruding on their driving style. If you’re consistently triggering DSC you are probably doing it wrong. (One exception might be if you’re running a tire combo where the front and rear revs-per-mile ratings on the tires are substantially different, in which case traction control and DSC may be more active than they might otherwise be.)

BRAKING - I was, frankly, underwhelmed with my brake performance, which is probably due to a combination of old rotors and less than ideal pads for my driving style and the weight of the car. I wasn't 100% sold on the EBC Yellowstuffs when I bought them but the price was right and reviews were decent so I went for it. I aggressively bed them in on a deserted country road before the event and could feel the pedal getting a bit deeper after the eleven 60-20 mph 80% braking events recommended by EBC. At all times the pedal felt just a tad softer than it was with the OEM pads.

On the track I can honestly say there were only 2 or 3 times over the course of the weekend where I noticed the brakes starting to fade a bit. I never felt like I'd lost them and I was always able to get the car slowed down with a bit more pedal pressure, but I can't say they were 100% consistent, either.

The brake fluid is generally regarded as some of the best around and I have complete faith in the mechanic that did the swap. So my disappointment lies somewhere in the pad/rotor combo. In the end I wish I’d ponied up a bit more coin for a proper set of full-on race pads. The upside of all this is the pads work perfectly fine on the street and haven't squeaked at all so far so I'll keep them on for the time being. They are putting out more brake dust than OEM so that will be what drives me to do the swap if I get sick of cleaning my wheels all the time.

All that said, the car had plenty of stopping power and was very well controlled under braking. There were some bumps in two of the heavy braking zones and by the end of the weekend I could consistently threshold brake without ABS right up to the bumpy spots, at which point the ABS would feed in about 3-4 clicks and then I’d be back to full threshold braking without ever adjusting my pedal pressure. I’ve read some things about just mashing on the pedal and allowing the ABS to do all the work for you. I tried that a couple of times and found it very unsettling to the car and I didn’t feel like I would be learning as much if I kept it up – you can’t really feel what’s going on with the ABS chattering away - so I made a point of relying on ABS as little as possible.

TIRES – As mentioned above I was running Continental ExtremeContact DW (not DWS) in 225/40/18 front and 255/35/18 rear. Wheels were stock style 162s with 8X18s showing the way for 8.5X18s – no spacers.

As written about extensively with these tires, there is a bit of delay between the moment you turn the wheel and the moment the tires respond. It’s tiny but noticeable. This would be infuriating at an autocross where direction changes are rapid and abrupt, but on the track it was mostly just something to get used to and became part of the rhythm of driving the car. There was one exception to this and that was the transition between turns 2 and 3, where the tires seemed a limiting factor in the ability to quickly change directions. Turns 1 and 2 are basically one long greater-than-180-degree sweeper to the right and turn 3 is a fast kink to the left. The moment you exit 2 (on the inside edge of the track) you are turning in to 3, so the car is going from very heavily loaded on the left side to very heavily loaded on the right side. I could really feel the “springs in series” during that transition with the tires and the suspension unloading and then reloading at the same time but at slightly different rates – creating a two-part transition. It felt a bit like the tires and suspension were raising the roof underneath me rather than working together to create a single smooth transition from one extreme to the other. I imagine a stiffer tire would eliminate one of those bumps and the car would smoothly roll from left to right – but quite frankly I don’t have the experience to say for certain whether that would be the case. Unsurprisingly there was no such sensation, at least from the passenger seat, in my instructors race-prepped E46 M3 on R-comps.

Grip wise in the dry the tires were quite good. They would howl nicely at the limit and screech when pushed beyond the limit – very good in the audible feedback department. Tactile feedback was also very good with the steering resistance dropping in a very linear fashion when reaching the limit. I was consistently battling understeer on corner entry and in a few places on corner exit, but that’s more a function of the driver and the relatively skinny 225s I had on the front. I suspect a 245 front would help tremendously with the understeer and my next set of tires will absolutely have at least a 4 as the second digit.

We had a very wet session early in day 1 and a fairly damp session early in day 2, and this is where these tires really seemed to shine compared to their closest competition from France. To me anyway, wet feedback was exceptional. I’ve always been terrified of even the slightest slide in the wet but on these tires it was a non-event – didn’t feel that much different than in the dry. Call me crazy but I really enjoyed those wet sessions. On the other hand, when chatting with other members of my run group after the wet session they seemed universally terrified. Nearly all of them were rolling on Pilot Super Sports.

Once things dried out and the tires started heating up I settled on about 31psi cold all the way around as the optimum pressure. On that weekend, in my car, on my tires, that corresponded to about 40 psi hot (or as hot as they happened to be after my cool-down lap and return to my parking *******.

TURNING – What’s to say? It turns like what it is, a 3-series BMW. Steering is balanced, consistent, and communicative. It’s not nearly as connected-feeling as a shifter cart, but what is? My goal in every corner was to make exactly one smooth steering input, hold position, and then slowly unwind the wheel as I exited. Any failure to do so was the fault of the driver, not the car. The steering that a lot of people complain about as being “heavy” felt absolutely perfect on the track. I always knew what the tires were doing, even in the wet. Approach the limit and steering resistance starts to drop. Cross the limit and the subtle vibes alert you to the folly of your ways.

The beauty of the balanced and consistent steering is that it allows you to steer with things other than the steering wheel, most notably the accelerator but also, in a handful of corners, with the brakes via trail braking. Turns 1 and 2 were the best place to practice steering with the throttle because you could initially set the car with the steering and still have enough turning left to do to experiment with the throttle. I gradually got more and more comfortable adjusting my line by adding or subtracting tiny bits of throttle. Tracking a little wide out of one? Remove a touch of pedal pressure and the rear end rotates nicely to get you pointed toward the apex. Coming in a bit tighter than you want? Add a touch of pressure and the entire car drifts ever-so-slightly toward the outer curbing. Too ham-footed on the throttle increase and you’ll be punished with understeer. Once I found the balance and rhythm of the corner, adjusting the line with the throttle became second nature and turns 1 and 2 became one of the most enjoyable parts of the track.

FINAL THOUGHTS – The bottom line is I had an absolute blast with my car and never felt like I didn’t belong on track with the gassers. The d was definitely a novelty and I got several comments from people that were surprised at how well it performed. My instructor was impressed at how much torque was available coming out of a corner at only 2000 RPM, something that seemed completely foreign to him. The only nit to pick with the car itself is that it’s a bit front heavy, but let’s face it, it’s a 4 door automatic diesel that gets 36 mpg on the highway, BMW didn’t design this car to be a track weapon, it designed it to be an efficient, comfortable highway cruiser. The fact that it performs so well on a track mixed in with M3s and 335s is a testament to the fundamental design elements underlying the E9X platform. I enjoyed every second I spent on the track and the car did, too.

This is probably more than enough for now. I'm doing some data analysis using information recorded by Harry's Lap Timer and coming up with some interesting graphs that I might share in a later post. If anyone has any questions that I didn't answer, feel free to post them and I'll do my best to respond.

STATS:
Best lap time: 1.51.56
Highest Cornering Gs – 1.1 (measured using Harry’s Lap Timer on an iphone 5S)
Top Speed Reached – 101 mph
Avg. MPG (day 2) – 7

[supermann125]

Great write up. I basically have the same car with same miles and have been itching to track it. Thanks for shedding light. And the average MPG

[brando1985]

Awesome writeup! Glad to hear everything went well. Here's a question you didn't answer- where's the GoPro footage?!

[Persian Whisperjet]

Great writeup!

[Yozh]

Originally Posted by gavronm

Once things dried out and the tires started heating up I settled on about 31psi cold all the way around as the optimum pressure. On that weekend, in my car, on my tires, that corresponded to about 40 psi hot (or as hot as they happened to be after my cool-down lap and return to my parking *******.

Thank you for such an enjoyable write-up. I was wondering why you chose such a low pressure for the tires? Recommended cold pressure is 35/42. I may not understand a few things, but when I ran a sport bike on a track we did not touch the standard pressure in the tires.

[335dFan]

Originally Posted by Yozh

Thank you for such an enjoyable write-up. I was wondering why you chose such a low pressure for the tires? Recommended cold pressure is 35/42. I may not understand a few things, but when I ran a sport bike on a track we did not touch the standard pressure in the tires.

I was curious about that too, but decided to remain silent until you brought it up. In my HPDEs, the instructor that I went with advised me to use 36psi all around, cold. I have a square setup though. I pretty much use 36 psi all the time now. The theory was to maintain neutrality.

[gavronm]

Originally Posted by Yozh

TI was wondering why you chose such a low pressure for the tires?

I didn't choose the final tire pressure, I arrived there after observing car behavior and reading the tires after the sessions. I kept track of my hot and cold tire pressures between each session.

On day one the track started out so wet the tires never really got hot and tire performance stayed the same through the first session. I was at about 38 cold. After 7 or 8 laps in the first completely dry session, when I'd started to really push the tires a bit, I could feel the fronts starting to go away. Mentioned it to my instructor and he suggested backing off for a lap or two to see if it helped. It did, and that was our indication that the tires were over-inflated. What happens is the air in the tire expands as it heats up, which increases pressure and causes the tire to balloon out. Instead of rolling on a nice flat contact patch you're now driving only on the middle part of the expanded tire. When I checked the tires after that session they were at 47 psi.

Looking at the tire after the session there was probably an inch of unused tread on the outside edges - Conti Extreme Contacts have a nice circle around the outside that tells you where the edge of the intended contact patch is.

So I took out about 4 psi, went out again in the dry, and it wasn't as bad but there was still just a bit of the tires going off at the very end of the session and when looking at the tire afterwords I was still about a 1/4 inch away from the circle - psi was around 42. Dropped another two psi and the next session out they were just right. They were a bit floppy for the first lap or two but once up to temperature they were perfectly consistent and the wear indications were right where they were supposed to be. After that they were consistently around 40 psi hot after each session.

There's no one "right" tire pressure. I wrenched for a 7 car vintage racing team for many years and we were adjusting tire pressures all the time based on tire pressures and temps that we checked and recorded immediately after each session. With those tires on those cars sometimes you'd start with 12 psi cold, sometimes you'd start with 18. It all depends on the weather, the track condition, who's driving the car, and how worn the tires are.

You need to feel for changes in the way the car is handling over the course of the session, check tire psi as soon as you pull in from a session while the tires are still hot (wear gloves!), and look at your tires to see how much or how little of the contact patch you're using.