When comparing a specific vehicle aviable in both AT & MT versions, the manual transmission will be quicker than th an the 'automatic'. That's mainly becaue there are power losses (heat dissipation) through the torque converter, a component employed on vehicles with automatic transmission. And the power losses here run approximately 13 - 16% from motor to the wheels. (Example, a stock Gen 6 ['98-'02] Accord V6 AT generates 200 max HP. However, COMPTECH's website dyno shows ~ 167 wheel HP, or approx. a 16% loss from the crankshaft to the rear wheels).In more detail, 'automatics' employ torque converters which are hydraulic 'couplers' between the crankshaft output & the automatic transmission input. Manual transmission in contrast typically employ dry clutch pressure plates...they introduce minimal slippage. Yet in the 'automatic', the torque converter is designed to slip at lower RPMs and then ultimately 'lock-up' at cruising speed. Again, there are power losses/inefficiencies inherrent in the design of automatic transmissions, & that's why the automatic transmission version of any car will be slower than the MT version.Examples of approx. 0-60 times:Gen 7 ('07) V6 Accord: AT ~ mid 6 sec. range; MT ~ 5.9 sec.Gen 3 ('06) Acura TL: AT ~ 6.4 sec.; MT ~ 5.9 sec.