The 2012 Toyota Prius Plug-In Hybrid is the second best-selling plug-in electric car in the U.S. today. It outsells the Nissan Leaf and is bested only by the Chevrolet Volt.
But if you view it as an electric car, it’s an odd duck indeed.
The car’s plug-in hybrid powertrain adds a 4.4-kilowatt-hour lithium-ion battery pack to what is essentially a standard Toyota Prius hybrid. That pack can be recharged by plugging it into a wall outlet.
The EPA says the Prius Plug-In has an electric range of 11 miles, though the small print notes that the car can only do 6 continuous miles electrically on the agency’s city test cycle.
That makes it the lowest-range “electric car” sold in the States, and the lowest-range plug-in hybrid as well.
Concentrating to keep it electric
Like the regular Prius, you have to drive gently and with some care to keep the car in electric mode. Even if you do, that doesn’t mean the engine won’t go on.
Having tested a Chevrolet Volt range-extended electric car the previous weekend, we found it disconcerting to unplug the Prius, get in, power the car up—and have the engine fire itself up within seconds. The Volt engine doesn't switch on until the pack is depleted.
The 60-kilowatt (83-horsepower) electric traction motor in the Prius is smaller than the Volt's 111-kW (149-hp) motor, by design. So the 98-hp 1.8-liter engine in the Prius still does the bulk of the propulsion work under heavy loads and at speeds over about 50 mph. Together, the engine and motor put out a maximum of 134 hp.
Moreover, the engine has to stay on enough to keep the catalytic converter heated up to the right temperature to reduce emissions. So even if you’re running all-electrically, you may stop at a traffic light and notice the engine thrumming away up there under the hood—even though the energy diagram doesn’t show it.
That’s all pretty discomfiting if you are trying to use the plug-in Prius like an electric car.
Electric vs. gasoline miles
The metric that Toyota would prefer you to use is the percent of time the car propels itself on electricity.
At the launch event outside San Diego in February, the test route covered a variety of city and suburban traffic conditions. We were able to spend a majority of each 5-mile route in all-electric mode, covering more than half of each electrically.
But that wasn’t the case over the course of our long weekend test drive. It covered a total of 326 miles, with about two-thirds freeway driving and one-third use around town.
Over that distance, the car managed to travel 11 percent (37 miles) in electric mode and 89 percent (289 miles) on gasoline.
Effective 54 mpg
The plug-in Prius was fairly efficient running on battery power—that 37 miles consumed 10 kWh—and the car told us we used only 6.0 gallons to cover the 289 miles on gasoline, or 48 mpg.
Once the pack is depleted, the Prius Plug-In is rated by the EPA at the same 50 mpg combined as the standard Prius hybrid. Our effective overall gas mileage for our total mileage across both modes was a modestly higher 54 mpg.
But to cover even that relatively low electric distance, we had to plug in the car half a dozen times over three days. The 4.4-kWh battery pack is by far the smallest of any plug-in, though Toyota believes it has optimized the car for overall efficiency.