How Consumer Reports tests cars:

Transmissions

Transmissions play a central role in delivering engine power to the wheels, of course, and the qualities of the transmission can greatly affect the overall driving experience. When evaluating automatic transmissions, our engineers look for responsiveness, how quickly and appropriately the transmission selects its gears, and also how seamlessly it shifts and downshifts. They assess how in tune the transmission is with the throttle, grade, and driver's inputs. For manual transmissions, the testers evaluate the shift action, how easy it is to move the shift lever through the shifter gate, and they gauge the feel of the stick shift in use. The appropriateness of gear ratios is taken into account too. The engineers also note the clutch action, looking for appropriate effort, pedal travel, and the point where the clutch engages the gearbox.