New Autocross Classes, beginning July 1, 2010

Our Chapter has a very popular Autocross Program largely due to the friendly and fun spirit at each event. Part of the welcoming atmosphere can be credited to our simple and objective car classes, making it easy to know exactly where your car fits. No complex points system, no intrusive tech inspections for modifications or challenges by intense competitors.

Recently, we have seen fewer 4 cylinder BMWs entered and a wider variety of 6 cylinder BMWs, no surprise with BMW’s current lineup. With the newer turbo cars, autocross times for 135i/335i drivers have approached M car times and leave early 6-cylinder BMWs in their wake, no matter how well-driven. The 6-8-12 cylinder class entry count has also grown, so we decided it was time to revisit our Autocross classifications that date back to the 80s. A committee was formed with the goal of creating one more category (with a Stock and Modified class), adding 4 more trophy winners (2 per new class), achieving a better balance of entries and still keeping it simple. We’ll keep the existing class structure through the 2010 Runoff on June 26-27, then open the second half of the year with new classes.

The Autocross committee wanted to keep changes to a minimum, so most classes remain the same. The backbone autocross car will always be the M3, and we’ve had recent top class times earned by drivers in E36, E46 and E92 M3s. As large as the M class is, there’s no clear way to break it down further among those M cars so they all remain together with trophies running 4 deep. Mini Cooper entry numbers still justify a single class, and we know Mini owners really enjoy competing with each other.

The obvious opening for a new category is between the 6-8-12 cylinder cars and the M cars. Rather than identifying each car by model (and having to update classes every time BMW introduced something new), we decided to define the new category by advertised stock horsepower. A new “T” class is added to split the 6-8-12 cylinder cars at the 295 hp point. M62 V8s (540i and 740i) have 282-290 hp, and BMW says the N54/N55 turbo engines (135i/335i/535i) have 300 hp, so 295 is a clean breakpoint. V8 and V12 entries are rare enough that we can’t justify a separate class, so they still fit in with the 6 cylinder cars. Under 295 hp includes E30s thru E46s and the naturally-aspirated E90s and Z cars, as well as the earlier V8 cars. Over 295 will separate out the turbo cars plus the later V8s (X45i and X50i models with 325-360-400 hp). Since E30 M3s and 6-cylinder M5 and M6s are both rare and achieve slower times on our long courses than later M cars, they have been added to this new T Class for a better fit. Note that our committee includes an owner of a 335i and an E30 M3. We created a Stock and a Modified class for this category, so that means 4 more trophies!

While revisiting the classes, we also made updates to the definition of Stock and Modified. Considering the autocross-specific performance of certain modifications and the popularity of some mods, we now allow engine software upgrades in Stock classes for naturally-aspirated cars (where it might add 10-20 hp) but NOT in turbo cars (where it can add 60-100+ hp). We also allow cold-air intakes, strut braces and any suspension bushings in Stock classes. And we have defined “R” compound tires (only allowed in Modified) as those with DOT treadwear of less than 140. Anyone driving on non-DOT tires (i.e. slicks) will automatically run in the Gold Class. The new classes are also re-named to be easier to remember and fit the most-common BMWs running in each class. We know that we can’t please absolutely everyone unless we have 100 different classes and 100 trophies for 100 drivers, but let’s remember this is all about having fun!

And now, here are the new Autocross Classes, effective July 1st, 2010:

Alternations permitted in Stock class

ANY other alternations are Modified Class, including: