Between the unexpectedly wild styling, the very wide model range, the Prius Prime plug-in, and now the all-wheel-drive 2019 Prius AWD-e, it seems that Toyota has opted for a mix-and-match philosophy for the current fourth generation of America’s favorite fuel-sipper.
The big news for 2019—and perhaps the biggest hope of all these tactics for slowing the Prius’ prolonged sales slide—is the addition of an all-wheel drive system, a feature that customers in cold-weather markets had sought. And it’s a feature we recently were able to test on snowy roads in Wisconsin.
Conceptually similar to the hybrid system used in the RAV4 Hybrid, the Prius AWD-e employs an electric motor to drive the rear wheels completely independent of the existing hybrid system powering the front wheels.
The motor is small, both in physical size and in its 7-horsepower output. This lets it sit beneath the rear cargo floor without intruding into the cabin space. The Prius’ hybrid-electric powertrain in front, making 121 horsepower and 105 lb-ft of torque, with a 1.8-liter inline-4, planetary-gear system, and two motor/generators, carries over intact.
Electric power for the all-wheel drive Prius comes from the kind of nickel-metal hydride battery pack employed by the base-level Prius Two in the car’s previous numerical trim lineup. This was selected for the nickel-metal hydride battery’s greater tolerance for cold temperatures than the lithium-ion chemistry used in the front-drive Prius models, according to deputy chief engineer Shoichi Kaneko.
The rear motor is a wound design rather than the permanent-magnet type used in the Prius’s electric motor-generators paired with the gasoline engine driving the front wheels. It doesn’t help provide regenerative braking, but it contributes no drag when it isn’t in use.
Which is actually a lot of the time. The rear motor’s main function is to assist with low-traction launches, especially when the car is facing uphill and the weight is shifted off the front wheels. It helps continuously at speeds up to 6 mph, then contributes as needed at speeds up to 43 mph (70 kph). Its design is optimized to function in this speed range, when all-wheel traction is viewed as most important, so it turns off at 43 mph.
2019 Toyota Prius AWD-e XLE - First Drive - Wisconsin, December 2018
The system adds 145 pounds of weight to LE models and 170 lbs. to XLE, due to unspecified differences between the cars. This extra weight, the limited operational range and paltry 7 horsepower from the rear motor mean that the AWD car is “the same or slower” than the regular front-drive Prius in 0-60 mph acceleration, according to Kaneko.
No difference, until the snow falls
On the road, the Prius AWD-e is indistinguishable from a regular Prius. On dry pavement on a cold day, the AWD does not chirp its front tires from the abrupt application of electric torque on takeoff from a stop, circumstances when the front-wheel-drive (FWD) car sometimes does, so that is a potential difference.