2008 BMW 135i: Track Day at Big Willow
January 16, 2009
Months ago, I lit into our long-term 2008 BMW 135i for having an insipid personality. But I didn't go to work yesterday. I took the day off and drove up to Willow Springs for an Evosport driving school on Big Willow. And there I buddied up with our 1 Series like never before.
Undoubtedly you've heard or know that Big Willow is a fast but not very technical track. Its turns don't require much actual turning, so if you have some idea about what you're doing, torque is pretty much all you need. The 135i has plenty of that. There doesn't seem to be a weak spot anywhere in its twin-turbo inline-6's powerband. As a track car, the 1 is incredibly user-friendly. It felt very quick, too, at full throttle down any straightaway.
Although I've criticized the 135i for not having good enough steering feel, the truth is that I knew exactly when the tires were gripping and when they weren't -- all that really matters on a track.
The One also has very strong brakes (13.3-inch front discs with 6-piston calipers, 12.8-inch rear discs with 2-piston calipers) and excellent pedal feel. It was very easy to skim off speed in preparation for Turn 1 at the end of the front straightaway. The brakes lasted well, too, and seemed none the worse for wear by the end of the day. But I can't say the same about the tires.
We knew going into it that this would be the last track day for the 135i's original equipment Bridgestone Potenza RE050A run-flat tires, size 215/40R18 85Y in front and P245/35R18 88Y in back. But when I went to refuel at lunchtime (after putting over 100 miles on the car during the morning session), I took one look at the left front tire and thought I might be done for the day.
In the morning, I'd set the tires (when warm) to 40 psi, which is 4 over the 36-psi cold spec. Either that wasn't enough for the fronts, or the camber settings weren't ideal for track use. Or, I wasn't doing enough to counteract the 135i's understeer. Probably all three.
Fortunately, most of the turns on Big Willow are right-handers, so the right front tire wasn't nearly as worn. A couple of the instructors and I did a left-right swap -- which is OK per Bridgestone for asymetrical, but non-directional tires. In the afternoon session, I tried to be less fussy at the steering wheel and rely on the throttle to correct my line -- obviously something I should be doing anyway. That got me another 125 miles at the track and another 90 all the way home to Santa Monica.
We'll be replacing all four tires very soon. Since the 135i is still in its first 12 months in our fleet, it's going to be another set of RE050A RFTs. You're welcome to try to talk us into something more interesting, though.
On Monday, I'll post a few more thoughts on my track day with our BMW 135i coupe. Until then, you can reacquaint yourself with the 135i's track outing at Spring Mountain Motorsports Ranch when it went up against our E46 M3 and a 335i.
Erin Riches, Senior Editor @ 16,234 miles