Originally Posted by Autobahn335i
Owning a highly modded 335i, here's my 2cents:
It all depends on your priorities and the depth of your pocket.
When I first got the 335i, I thought performance and handling were great. But as you get used to the car, you realize the shortcomings (handling mostly) and the potential (performance). That's where the modding started and things got ugly
Not going into full details, but let's say that $30k in mods later, I have a car which makes me not long for an M3
Did I expect to dump that much in the car when I got it? No way!! But both the mod bug and the tracking bug bit me badly! And to make a 335i perform and be reliable on a racetrack takes alot of work. But to some extent the same applies to the M3. And modding an M3 is even more expensive.
My verdict is that if you're looking into a complete sports car package from the factory, the M3 may be a better choice.
If you're not afraid to go down the slippery modding slope, the 335i has a LOT of potential while still maintaining it's advantages: way better mpg (gas prices in Europe are high and driving to the gas station weekly would piss me off), heaps of torque at low/mid rpm (great for daily driving), lower insurance and running costs.
I agree that it would cost a lot more money to make a 335 competent on the track and reliability is always going to be on the back of your mind with the high pressure fuel pump even though they seem to have much less reliability issues running on the gas you have over there. The M3 is track ready out of the box other than perhaps getting better brake pads so absolutely no additional expense is required. I see that you've slapped M3 suspension parts and a limited slip diff on your 335 but that still won't give you the versatility of EDC and the performance oriented MDM not to mention the M-DCT. In the end, pouring that 30k into your 335i would probably not get you around the Nurburgring faster than my time of 8:07 in light traffic on a tourist day with a completely stock M3. The lower running cost and insurance does not apply here.
In conclusion, if you are going to take the car to the track, get a M3 period. I'm glad you made your 335i work for you but if you could do it all over again knowing how much money you would eventually pour into it, would you have reconsidered getting a M3 instead? I'm a 335i to M3 convert and I would have gone with the M3 from the beginning knowing what I know now.