have a pretty wide rev range, they produce a bunch of torque at low rpm and they're sufficiently efficient across that rev band. For that reason, most EVs make do with a single-speed transmission that has its gearing set up to balance all of those qualities in equal measure. That doesn't mean the single-speed EV transmission is as good as it gets, though, and thinks it's cooked up something clever that can produce even more benefits.
ZF on Tuesday unveiled a new two-speed transmission. Dedicated for electric vehicles, ZF believes its technology can improve a vehicle's efficiency without taking up an unnecessarily large amount of space, which would only work against the new transmission's efforts.
This new two-speed unit is programmed to shift at about 43 miles per hour, but that shift position isn't set in stone. It can work with a car's other systems to, for example, choose when to shift based on local maps and topography. It could also shift into a more range-minded gear based on its distance from the next EV charger to help alleviate range anxiety.
By implementing this second gear, which can provide a ratio more suited to efficiency, ZF claims its transmission can boost range by up to 5 percent when compared with a single-speed unit. Automakers could pair this with a smaller battery, reducing curb weight while maintaining range, or it could use the same battery for additional range.
ZF believes there's use for a two-speed transmission beyond efficiency, too. By tweaking the gear ratios, ZF could instead create a transmission gearing that boosts an electric car's top speed -- a notable sticking point for some EVs, which have rev-limited top speeds in exchange for better low-speed performance. We'll get our first glimpse at a production EV with a two-speed transmission when thecomes out, although it's unclear if Porsche is relying on ZF's solution or if there's another one kicking around.