Originally Posted by warranty
OP, I just recently purchased an E90 M3 myself and went through some of the same thought processes as you: 335i or M3? Like you, I need a 4-door (kiddie taxi), and I live & work in Bay Area so I know that most of the time I'd be driving way under the speed limit--probably in traffic--so fuel economy is a factor, and there's some of that "is it really worth the extra $$ just to have a few seconds of more fun a day?" question.
Honestly, for me the dilemma came down to be about money, and I imagine it's probably the same for you (but I can't speak for you): am I willing to spend a little more to purchase and run an M3, or put that money towards something else? At the end, I said "f*ck it, I've done a lot to save and provide for my family, now I want to get something DADDY WANTS."
Somebody else put it very succinctly this way: 335 enthusiasts will wish they could upgrade to an M3, but no M3 driver would ever wish they had gone with a 335 instead. It's simple as that. 335 is a nice car in its own right, but M3 is much more special. It's a dream car for those of us who need 4 doors.
So, I can't tell you what to do, but I'll tell you this: now that I got the M3, I've never again even spent a nanosecond thinking about "what if I saved the money and got a 335i instead?". On the contrary, I have a ear-to-ear shit-eating grin on my face every time I get behind the wheel of my M3...even in traffic. Why, all the more reason to row through the gears of my 6MT! Heck, even going to the store to get diapers is fun because staring at that power dome reminds you that you're going to get Huggies in machine engineered by gearheads who accepted very little compromises.
I am the OP and welcome the many responses. Many were helpful (with a few exceptions). Responses by TTG, ADC, Pharmdphd98, Warranty, and others were good.
The bolded sections above hit home. Yes, the M3 IS special. It may not be needed or ideal for my driving environment, but just driving a car like this, at ANY time, ANYWHERE can be rewarding. Those comments reminded me that I found my old M3 enjoyable ALL the time, whether through a school zone, pulling hard at high rpm, or flinging it down a back road, or just a brisk ride with wife and daughter.
My Porsche Cayman S is more narrowly focused with more compromises for street driving which is what gave me pause on the new M3. Has the focus on constantly increased performance (great!) resulted in compromises in the M3 that are really just too much for a typical urban environment?
Responses so far make it easier now to understand the real question. Of course the 335i (or something far less) is the best sedan for the majority of my driving...if you look at it from a purely practical point of view and exclude
passion and lust for fine performance engineering that sits in your garage, ready to devour pavement, straight or winding, with grace, speed, control, precision, luxury, and sound. You may not use all it can offer, but you can still feel and enjoy a lot of the soul of the car at any speed