It's been a long time since any production cars have used 2-speed automatic transmissions. 

With a new 2-speed transmission for electric cars, German supplier ZF Friedrichshafen is turning back the page on EV development. 

The clutchless 2-speed transmission Tesla attempted to use in the original Roadster found notoriety for the lengthy delay of that car it caused due to reliability struggles. Eventually the company just went with a single gear that drivers didn't have to shift.

Customers didn't seem to miss the extra gear, or the shifting, and every volume-production electric car since has only had a single gear.

ZF Friedrichshafen 2-speed EV transmission

ZF Friedrichshafen 2-speed EV transmission

ZF thinks that may not be good enough. It's designed a new one to pair with more powerful motors, to allow electric cars to do more.

Many automakers with electric cars gear them to top out at about 125 mph (if not before then). But that's left some of them to use a bigger motor than they need, paired with a taller ratio than they might ideally want for city driving.

"Until now, with electric motors, vehicle manufacturers have had to choose between high initial torque and a high top speed," said Bert Hellwig, head of e-mobility systems at ZF, in a release. "We are now resolving this conflict and the new drive will be compatible for performance and heavier vehicles,"

Tesla Roadster Prototype for sale on eBay

Tesla Roadster Prototype for sale on eBay

As an example, electric SUVs or pickups that tow trailers could benefit from having multiple gear ratios to maximize power at low speeds without sacrificing efficiency. High-performance sports cars such as the Tesla Roadster could also gain higher top speed with access to a higher second gear.

ZF estimates that the improved efficiency at high speeds could deliver 5 percent more highway range for an EV. 

As electric automakers chase after every mile of range while keeping a lid on battery cost and weight, every little bit of added efficiency helps.

So far, ZF has made no announcement what automakers might use the 2-speed transmission in upcoming electric cars.