my dads got a an A4 3.0 TDi Quattro and although i havent driven it yet in car it feels as quick if not quicker in the right circumstacnes than my Z. i just never really feels like your giving it the beans even when it pulling like a train the short blips of power you get in a diesel dont compare to that racey feel of raw NA power, guess thats hwy you dont get any diesel sports cars. i mean imagine a Z with 335d+ chipped engine.. great mpg , fast , handles well and cool Z looks. you just dont have that Z growl.