As of February 23, 2004, GM's Proving Grounds testing has resulted in a 2005 Z51 Targa going 0-60 in 4.2-sec. and a base Targa doing it in 4.3-sec. The quarter mile performance of the Z51 was 12.6-sec at 115 mph and observed top speed was 186 mph. this is NOT the Z06 version. these are base model performance numbers.