Never mind ‘autonomous’ cars, the debate is not over with ‘auto’ versus ‘manual’ gearboxes. Forgetting personal preferences for a minute, much has to do with the intended use of the vehicle.
Modern automatic transmissions go back to an early “horseless carriage” gearbox developed in 1904 by the Sturtevant brothers of Boston, Massachusetts. This unit had two forward speeds, the ratio change being brought about by flyweights that were driven by the engine. At higher engine speeds, high gear was engaged. As the vehicle slowed down and engine RPM decreased, the gearbox would shift back to low. Unfortunately, the metallurgy of the time was not up to the task, and owing to the abruptness of the gear change, the transmission would often fail without warning.
Today’s automatic gearboxes have grown from two speed autos to currently a nine speed being the maximum number of ratios. ZF Friedrichshafen and BMW were responsible for introducing the first six-speed (the ZF 6HP26 in the 2002 BMW E65 7-Series). Mercedes-Benz’s 7G-Tronic was the first seven-speed in 2003, with Toyota introducing an eight-speed in 2007 on the Lexus LS 460. Derived from the 7G-Tronic, Mercedes-Benz unveiled a semi-automatic transmission with the torque converter replaced with a wet multi clutch called the AMG Speed Shift MCT. The 2014 Jeep Cherokee has the world’s first nine-speed automatic transmission for a passenger vehicle to market.
Following the acceptance by the marketplace of auto transmissions in the 60’s, comparisons started to be made between the two types, with manuals favored because of fuel economy, and also quicker in acceleration. But that was not to last, clever engineers developed the twin-clutch auto transmissions which are now quicker than even the most enthusiastic driver in a manual.
Manuals can be more affordable, and more economical, and with the more vital driver involvement, still seem to win plenty of fans in Europe, where they are still a popular choice (in the UK for example, 75 percent of cars sold in 2013 were manual equipped), but in the US 93 percent of all cars sold are automatic. One should also remember that automatic transmissions are easier on the drive train and eminently more relaxing to drive in stop-start city driving.
So what do I drive? Quite frankly, for round town, give me my automatic any day, but for the race track, it must be a manual to give me (the driver) that sense of control at all times (even though it may not be). I suppose it’s because I like to know what gear I am in, and not some ratio the electronic brain thinks would be better.