2019 TOYOTA PRIUS AWD-E FIRST DRIVE: THE HOKKAIDO BUTTERFLY EFFECT

Several years ago, some Toyota Prius driver (whom we'll probably never know) was living in Japan's cold northern island of Hokkaido and having trouble getting enough grip on a snowy day. Toyotabegan to hear other stories like this, so it came up with a simple, low-cost solution: a small electric motor on the rear axle that was tuned purely to help get the otherwise front-drive Prius moving on the crunchy white fluff.

Once underway, the motor would de-energize and freewheel to maintain the car's precious efficiency. Parasitic drag would be minimal because the motor is the induction type, due to switchable electromagnets instead of permanent ones. And to feed its periodic electrical hunger pangs, the battery chemistry was swapped to faster-discharging nickel-metal hydride. It's a characteristically elegant, light-touch solution. If Toyota is great at engineering, it's a long-distance military sniper when it comes to targeting a feature's cost-benefit sweet spot. Called the Prius E-Four, it's been quietly rolling out of Japanese showrooms ever since.

Three years later and 6,000 miles away, the U.S. car market is in upheaval as the crossover craze is eating sedan sales to the bone. One notably skeletal example being the Prius liftback that's been diminished to a startlingly mere 50,000 annual sales, the bone-bleaching so far unresisted by any of the gas spikes that periodically revive it.

What to do? Toyota's California island of Prius sales desperately needs to colonize the northeast, which is presumably sympathetic to the car's environmental arguments. But it snows there, so they buy Subarus instead.

At this point I'd like to imagine some Toyota sales executive's eyes suddenly widening hey, what about the Prius E-Four?

It's a natural. Renamed the AWD-e for us, the all-wheel-drive variant will be available only for the Prius' LE and XLE trims (bracketed below by the base L Eco and above by the Limited—all four replacing the millennial-talk Prius 1, 2, 3 and 4). Visually, the car's nose and tail have been undergone the usual midcycle nip-tuck, emerging with less frenzied headlights and a Camry/Corolla-like trapezoidal air intake. Its lower corners point to where the front wheels contact with the ground, we're told to telegraph stability. At back, the giant vertical lightning-bolt taillights have turned 90 degrees and receded in scale; the look is altogether less Prius-polarizing. It's the same inside were the blanch-white shifter surround has been decontrasted into either gloss or flat black. The user interface is friendlier, too, with easier-access seat heater switches, a bigger platform for inductively charging bigger smart phones, and twin rear-row USB ports.

To get its U.S. green card, the E-Four system requires a bit more rear crash structure (an aftereffect being the exhaust tip's subtly downturned angle). Together with the electric motor, AWD-e's weight ticks up by about 160 pounds. Countering this is a slight drop in the front powertrain's gearing, while the little motor's 7.1 hp and 40.6 lb-ft pitches in up to 6 mph. It continues after that only if wheel slip is detected, signing off completely at 43 mph. On a dry surface, the Prius AWD-e is probably a tick slower.

Ground clearance is essentially unchanged (OK, 0.2 inch higher) and the low rolling resistance tires are identical, so forget the off-road fantasies. But with the help of a snow blower (the weather in Kohler, Wisconsin, wasn't being cooperative for testing, even in December) Toyota replicated a real-world, got-to-get-to-work, slippery white carpet over which the Prius AWD-e magically accelerated, stopped on a little incline, then resumed uphill again without a whiff of the front-wheel hole-digging you'd expect. It works. The rear differential is open, so metering the 7.1 hp laterally is by automated left or right brake squeezes. Noodle the steering wheel off-center, and you might detect a touch of extra rear weight—as if there's somebody in the back seat. At least it's a passenger that won't argue over the radio station. (Speaking of which, no passenger or cargo space is sacrificed to the system.)

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Despite the rear motor never mining any regen energy (the small battery being more of a quick, in-n-out energy slush fund) the AWD-e system barely dings the car's mileage, estimated to slip a scant 2 mpg in both city and highway mpg, combining for a still Prius-proud 50 mpg. At a sensible price premium of $1,400 for the LE and $1,000 for the XLE, Toyota expects the AWD version to capture 25 percent of future sales.

Which, along with the FWD Prius's submarining sales level, is stunningly depressing. If the reasons were just lowish gas prices and the crossover frenzy well, whatever. But if the UN's recent report by the Intergovernmental Panel on Climate Change was pictured as an asteroid barreling toward the planet, which we can help divert by driving a 50 mpg AWD sedan—well, why not?

Taming CO2 rates probably requires a faster transition to fully electric propulsion than the Model 3 and a smattering of $100,000 European EV's can provide, yet these right-now solutions are struggling (with the Chevrolet Volt in cardiac arrest). The dinosaurs are not looking up to the skies again. But if—from our dinosaur-scale SUVs—we actually did look up and around, we might be charmed that part of the answer began, inadvertently, with some drivers in Japan who, a few years ago, asked for a little better grip in their island's snow. It was the Hokkaido butterfly effect.