It's all a matter of good timing and luck in KL. Not so easy to spot Murcielagos, that's for sure - they're probably the least common cars... But quite a few 360's and Gallardos are running around... Even more Porsches.
Best time to spot would be weekend, best places are:
BSC, Bangsar
Bangsar Village II, Bangsar
Pavilion, Bintang Walk
JW Marriott hotel, Bintang Walk
Mandarin Oriental (quite rare), KLCC
Hotel Equatorial, Jln Sultan Ismain (quite rare)
Shangri-La, Jln Sultan Ismail
Hard-Rock Cafe/Concorde hotel, Jln Sultan Ismail (not so often)
Prince hotel, Jln Raja Chulan (thats where TMJ's convoy usually stays, but he comes to KL very seldom)
That's where I see most nice cars...
there is a Residences hotel in heart of KL that has modena 430 x 2, 460, amg SL55 X 2 amongst others. the cars in there are very impressive.