OP what about a 335d? You won't have the risk of the reliability issues that some 335i's have been having (not to suggest they're common or widespread, but they're definitely there) and you get monster torque. If you don't intend to EVER take the M3 to the track or at least go out frequently for long drives on twisty roads I think it would be a bit of a waste. The 335i and especially 335d make better commuters because they have more low-end torque. Is the M3 faster? Yes, absolutely, but to achieve that you need to be roaring around in lower gears at high RPMs, which not only kills your already bad gas mileage but is pretty obnoxious in the city -- though it's definitely a lot of fun on the track and in back country roads. But meanwhile the 335i and 335d can deliver instant bursts of acceleration with less drama and possibly no gear change, will cost less in gas and insurance, and both will likely be cheaper to maintain because they're not M cars. That last will be especially true of the 335d which as far as I know hasn't had any major issues.
That said, the M3 has thus far proven to be one of the most reliable cars in BMW's current lineup, but again if anything does go wrong you'll be looking at expensive repairs even by BMW standards. It'd be hard to estimate maintenance costs at this point though because the very first 2008 M3s that rolled off the line would be just now coming out of their 4-year warranty and free maintenance periods, except for the relatively few that might have run those out earlier based on 50K miles rather than time.
Last edited by jphughan; 09-08-2011 at 11:29 AM.