Engines might be getting smaller in the pursuit of saving fuel but transmissions are going the opposite direction.

Over the last few years different carmakers have rapidly increased the number of ratios available to drivers, with Mercedes-Benz giving us 7-speed autos, Lexus developing an 8-speed and ZF recently announcing a 9-speed auto transmission. According to Bloomberg (via Automotive News - subscription required), Hyundai now has a 10-speed auto in the works.

It's all about economy and performance benefits. To make the most of both, an engine must work at a speed that maximizes its spread of power and torque, and more ratios help achieve that.

This is particularly important in the new generation of downsized engines. Despite turbocharging, new engines might not have as wide a spread of torque as older, large capacity engines, so multiple ratios helps offset this.

This means multi-speed transmissions can be more precise about dropping down gears on freeway inclines to avoid soaring, gas-guzzling revs, and change up sooner for improved economy in city driving, without sacrificing performance when it's needed.

Modern autos are smooth enough that changes are nearly imperceptible, so there's no refinement penalty for chucking ever more ratios into the box.

The new transmission is expected to appear in Hyundai luxury vehicles from 2014, most likely the Genesis and Equus luxury sedans.

With downsized four-cylinder engines becoming the norm, how long will it be until the transmission is bigger than the engine itself?...


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