Acceleration

Straight-line acceleration consists of three different tests: the standing start (from which we pull all the zero-to-speed times), the 5-to-60-mph rolling start, and two top-gear acceleration tests (30 to 50 mph and 50 to 70 mph). The rolling start is a C/D creation, in which we creep along at 5 mph and then accelerate as hard as possible. This test illuminates differences in powertrain flexibility. The larger the difference between a 5-to-60-mph and a zero-to-60-mph run, the more lag an engine has; this is particularly relevant today with the flurry of turbocharged engines. Top-gear acceleration, in a manual-transmission car, where we simply goose the throttle and don't downshift, highlights midrange power. In a vehicle with an automatic, the transmission downshifts (and the times are much quicker), so this metric represents a combination of transmission and engine responsiveness. And that means the times between vehicles equipped with manual and automatic transmissions clearly aren't comparable.