Hymotion Conversion Plug-In Prius: First Drive

So how does it drive?

What’s going on in the background isn’t exactly the same, though. The L5 battery can only be charged by plugging the car into 110-volt household power using a connector in the rear bumper. It doesn’t recharge through regenerative braking, and it can’t be recharged by the engine. A normal Prius starts the engine when its battery drains down — but having a full Hymotion pack onboard keeps the Prius from doing so. This step, along with the fact that the car leaves home with a larger, topped-off battery, gives the converted Prius 30-40 miles of up to 100-mpg driving, according to Hymotion.

Once the L5 battery is depleted, the Prius operates as any unconverted one would — with an extra 180 pounds onboard. The driver can keep an eye on the charge state of both battery packs on the LCD screen’s Energy Monitor display. The L5’s charge level appears as a green bar graph that overlays the regular battery pack’s blue one.

Hymotion isn’t the only company providing plug-in solutions. Many individuals and companies have converted hybrids — mostly Priuses — leading environmentalists to ask, “If these guys can do it in their garages, why can’t the automakers get it together?” The main reason is automakers have to make their products reliable, safe and clean. At this stage, converted cars are exempt from safety and emissions requirements, but Hymotion says the L5 pack has no effect on a Prius’ pollution levels, and it’s also the only conversion product that’s government certified for rear crash safety. As such, it occupies the middle ground between conversions of unknown performance — and mass-market cars that just aren’t here yet.