What makes a M series car different from a 3 series?
 

Everybody I ask cannot give me a legit answer. I know they are "suped up", but how?

What makes it different besides the fact that the car is tuned by BMW Motorsports branch ,engine with more HP , suspension setup and ride height, steering, gearbox (SMG), interior, body panels,wheels and tires ???

Yup, Danny's got it right. Although the SMG box didn't happen until the E46 M3.

Subjectively, M cars feel tighter, less body roll, more road feel, engines more responsive---than "ordinary" Bimmers.

Plus when you modify M cars, you start with such a good base that you can really come up with some sweet motoring!

Bruce M.
1978 930 (heavy mods)
1998 Dinan SC M3 coupe

Right-o. It's basically cheaper to modify an 'M' series car that already has all the goodies from teh factory, than start out with a regular car that you need to add all of the performance parts to.

M 3-series can be best compared to a Porsche RS Touring vehicle. All the race stuff, but without the weight cuts (still comes with A/C, etc...)

-Wayne

///m just starts with a stock 3 series, stiffens the chasis with various braces, changes the suspension geometry a bit for more aggressive driving (for example the rear trailing arms and front A arms are all stamped "///M" on e36 cars), then they add stiffer and lower springs and shocks, sway bars... next they beef up the brakes and wheels/tires...

then they build a different motor, the e36 m3 had a massaged 325 motor, the new ones (333hp e46) use a S54 engine which shares nothing with the normal motor... they go on to add a stronger transmission and differential, the rear subframe is reinforced.

then the do all there normal bodywork shiat, and dress the interior up...

soo pretty much the only part left alone on an M car is the monoque / tub.