Automatic transmissions are a godsend. They allow us to drive without working our left feet and enable us to keep both our hands on the wheel; just put it in “D” and go. No wonder that last year, according to the EPA, 97% of all cars had just 2 pedals. But then there are enthusiasts, luddites who love inconvenience, that scoff at automatics, labelling them as “slushboxes”. They claim that stirring through the gears and working the clutch is fun. But let’s just forget about these weirdos for a minute and focus on the history of one of the greatest inventions in automotive history.
Automatic cars, if not automatic transmissions, have been with us since the birth of the automobile really. In the 1910s, it was a 3 way race between internal combustion, steam, and electric. The latter 2 produced so much torque that they didn’t need transmissions at all. But electric cars took too long to charge and had very short range while steam cars were heavy and consumed huge amounts of water. Internal combustion engines do not produce enough torque to get going, so they needed gears. In the 20s, once internal combustion established its dominance after the electric starter was invented and eliminated wrist-breaking crank starters, engineers worked to automate the process of changing gears.
The first automatic transmission in a production car was GM’s Hydramatic, introduced in 1939 in Cadillac and Oldsmobile. The transmission had 4 forward gears and power came from the engine through a fluid coupling. The transmission was not as fast or efficient as a manual but buyers loved resting their right arms. By February 1942, when civilian automobile production stopped due to the war, 200,000 had been sold. In 1948, Hydramatic made it to Pontiac, where the take-up rate was 70%. Buick and Chevrolet chose to develop their own automatics, Dynaflow and Powerglide, respectively. After a fire at the factory that made Hydramatics in 1953, Olds and Cadillac had to use Dynaflow and Pontiac used Powerglide for a time. The original Hydramatic was retired in 1956 although the name would be used until the 90s. GM had established the automatic to the public and by 1960, 70% of all cars in America had 2 pedals. The take up rate in Europe was much slower, due to the much higher price of gas.
It is remarkable how long it took everyone else to offer a fully automatic transmission. Ford finally offered one in 1950, the Ford O-Matic, developed by BorgWarner. Ford’s contribution did offer an advance over GM’s: a torque converter. A torque converter multiplies torque, as the name implies, through the use of a stator (explained here). Packard had introduced such a feature in 1949 with their Ultramatic, but that wasn’t a fully automatic system. Packard also incorporated a lock up clutch which at high speeds bypassed the torque converter and avoided the associated energy losses. This system was not adopted until later because of the cost and complexity. Chrysler, after toying around with semiautomatics that got rid of the clutch pedal but still required manual gear changes, finally joined the party with Powerflite in 1954. Smaller automakers, especially foreign ones, usually bought them from GM or BorgWarner. In 1969, the German company ZF began making its own and would come to dominate the field in due course.
In 1958, a Dutch automaker called DAF came up with a system that allowed variable ratio gearing rather than began stuck with a finite number of fixed ratios. It was the first continuously variable transmission in a production car. It offered improved fuel economy over a conventional automatic while retaining the convenience, but owners who were used to their engines revving faster as their speed increased were weirded out by how the CVT kept the engine speed constant. Also, during acceleration, the CVT would keep the revs high and produce lots of noise. Those rubber bands also weren’t as durable as steel gears.
The energy crises in the 1970s meant big changes were needed. Packard’s old lock-up torque converter system was revived. Most cars had 3 forward speeds, but now a 4th overdrive gear became ubiquitous. The extra gear means lower revs on the highway, which improves efficiency. By 1990, the 4 speed automatic was virtually ubiquitous and had seen few changes in 15 years besides the addition of electronic control.
Then, in 1991, BMW brought out the first ever 5 speed automatic transmission on their flagship 7 series. By 2000, 5 speeds would be the standard for most luxury cars.
In 2002, the BMW 7 series once again led the way. It was hideous to look at and had a diabolical iDrive electronic control system, but it had the first ever 6 speed automatic transmission. And so would begin a singularity of gear numbers. The 6 speed would catch on much faster than the 5 speed did. My 2009 VW Rabbit has 6 gears.
Just 1 year later, Mercedes upped the ante with a 7 speed automatic on the S430 and S500, and it would become standard on most of their models after 2007.
In 2003, we got another type of transmission when VW introduced a dual clutch automated manual in the Golf R32. The system gets rid of the torque converter in favor of a pair of wet clutches. This allows for extremely quick shifting and became popular on many sports cars. Ferrari in fact dropped all stick shifts in 2012 and now only uses this twin clutch system.
In 2007, Lexus brought out a new version of their LS flagship. It had, you guessed it, an 8 speed automatic.
The CVT also saw a revival during this time. Saturn, Mini, and Ford all offered it briefly then dropped it. Nissan’s Xtronic would be offered on pretty much every car they sold, even the large Maxima and Murano. In the 2010s, it would become the standard transmission in economy cars.
The next 7 years was sort of a catch up period as the last 4 and 5 speeds were dropped and everything moved either to an 8 speed or a CVT. By this point, thanks to the extra gears and better electronics, automatics were now actually faster and more fuel efficient than manuals. Then we got our first 9 speed. This time, it wasn’t on a giant luxury sedan, but on a small SUV, the 2014 Jeep Cherokee. It’s just as well because there were many initial problems with noise and slow shifting, and it would have been a shame to have those problems in a Mercedes S class.
In 2017, we got the first 10 speed automatic. It was a joint venture between Ford and GM and first used in the F-150 and Camaro ZL1. And before you ask, both Ford and Honda have patented 11 speed transmissions.
This is what the explosion in the number of automatic forward gears has looked like, according to the EPA. It took us 20 years (1980 to 2000) to go from an average of 3 gears to 4 on passenger cars. It only took us 10 (2000 to 2010) to go from 4 to 5. It only took us 4 years (2010 to 2014) to get from 5 to 6 and now we’ve levelled off at about 6.5.
But in truth, the future is probably going to be no gears at all. As I said before, electrics produce so much torque that they don’t need any assistance from a complicated, heavy, and expensive transmission. And extra gears are subject to diminishing returns and there’ll be a point, one which we may have already reached, where the extra cost and complexity of more gears won’t be worth it.
So that’s the automatic transmission. A wondrous invention that has made driving easier and simpler for all. And to the enthusiasts who whine about people missing the “joy” of wearing out your left foot and right arm: they can shove their clutch pedals where the sun don’t shine.