I own a 2002 M3 and a friend of mine owns a 2000 M5 and i would say they are fairly different . I have topaz blue with cloth interior while he has carbon black with carmel luxery package interior and just that makes a huge difference in the fee, the M3 is a much more ports car feel while the M5 is the ultimate cross over IMHO it is as fast as a sports car but is still a luxery car . Both cars have adequate room but M5 is much better if you wanna haul people around . He has the wood trim so it looks more luxerious inside but i knwoy uo can get a sport trim if thats the look you want . As for performance i would say an M3 is slightly faster till you hit high speeds but the M5 is easier to get to go faster with all the low tourque and really you can't tell a good enough difference as to which is faster . I would go with an M3 because it had what I wanted but the M5 is one hell of a beast so you can't go wrong either way !!!!!!=) -Jarrette