I had a 2008 135I for two years and 18000 miles. It was a 6 speed manual pretty much a base car with just a few options. The car had chronic high pressure fuel pump issues it went through 3 of them.The fuel pump issues ranged from the car going into limp mode or on one occasion getting on the freeway it just died. On another bad pump it would just not restart at the grocery store had to have it towed in. Performance wise I have had both it ,and the SRT6 at the track. The BMW was stock except for bfg drag radials,and a K& N filter. With the manual transmission it would not hook up with the stock tires. The SRT6 is stock except for the Needswings cai. The 1/4 mile times for these cars is almost identical. The BMW was faster @ 60' with the drag radials(1.9 vs 2.20). The SRT6 had a higher top end speed(103 vs 99) and it liked the end of the track better. I would say an auto 135I especially one with a chip will be faster, and win a drag race. What I found interesting was the 135I feels way faster the turbos really come on and give the impression of fast acceleration. The SRT6 is deceiving it just doesn't feel as fast as it is. I raced at Bandimere Speedway where the air is thin an average DA there is 8000'+. My corrected time in both cars was 13.3.