WHERE CAN I HIRE A FAST CAR IN BANGKOK

HI AGAIN TO MY THAI FRIENDS,YES I M GOING TO THAT BIG MANGO ,I NEED TO FIND A HIRE COMPANY THAT HAND S OUT GOOD CARS ,I PREFER AN S6 AUDI BUT THAT MIGHT BE ASKING TOO MUCH,CAN SOME ONE HELP ME ON THIS.
ALSO IF THERE ARE ANY HK MEMBERS IM LOOKING TO BUT A 500SL OR 600SL 1990 MODEL VEHICLE MUST BE 15 TRS OR OLDER FOR AUSTRALIAN IMPORT LAWS.WHERE Can i start.
in thailand they take your licence when your booked ,should i get some copys before i arrive in thailand.

regards
tom