The Toyota Prius Plug-In Hybrid I was lucky enough to test drive for a week (complete with flashy side decals so everyone knew what I was driving) was one of the fleet of demonstrator cars making the rounds of press, academic, and industry types here in the U.S. The program gives Toyota feedback on the technology as well as user experience and expectations.
The car had a prototype Li-ion battery with 5.2 kWh capacity. Toyota says a production version of the battery will likely be reconfigured to better fit the available space (the rear deck lid is fairly high on the demonstrator) by the time production cars are sold starting in early 2012 (Sales will start in the 13 states that have adopted the California Zero Emissions Vehicle mandate).
The "electric range" reserve of the battery was depleted when the car arrived (with a full tank of gas). It took only three hours to recharge the battery (using the 110V charger that came with the car), which then allowed the car to go 13 to 14 miles in an EV only mode. But the plug-in Prius is no slouch on only electric power and runs at up to 60+ mph without using the gas engine. If you stomp the throttle while in the EV mode, the internal combustion engine will come on for additional power.
Sizing the battery for the 13 mi EV range was a compromise between "size, weight, and cost of the lithium-ion battery pack, all of which we wanted to keep within reasonable limits," said Toyota spokesman Wade Hoyt. If one's driving is less than or not much more than 13 miles until you're back home or near an outlet for a short charge, this editor can see the plug-in becoming an "in-town" electric vehicle.
The charging process itself had the same minor problem I experienced with the all-electric Nissan Leaf
, namely the outlet plug slipped from the wall socket if the power electronics control box on the cord was not supported.
Charging was aided by a "time to full charge" readout in the driver's center display. There was also a light on the dash visible from outside the car that goes out when the battery is fully charged. While on the charger, the driver is able to turn on the air conditioning, via the key fob, to precool the car in the summer using utility power. But there is no similar heating function for colder weather. I was also wondering why no remote window-roll-down feature is offered to help with summer cooling without use of the air conditioning.
On the road
Push the "start" button in the plug-in Prius and a "ready" light comes on to let you know all systems are go—the gas engine did not come on (as is often the case in a standard Prius to get it warmed up). I don't know if this was because my drive was in the summer weather or not. A self-centering shift "lever" (it's more like a sliding knob) puts the automatic transmission in the reverse, forward, or engine braking modes. The latter uses more aggresive engine braking to slow the car—but if you forget to return to the drive position, the cruise control won't activate.
But the big question with any alternative powertrain car is what was the fuel economy. First off, I noticed just a slight dip (only 0.1 miles) in the remaining EV range number when I switch on the climate control. After 310.4 miles, I filled up with 5.168 gallons of gas, for a mileage of 60.1 mpg (the onboard computer pegged mileage at 59.8 mpg). If you eliminate the electric range only mileage (I charged and depelete the battery through four complete EV cycles for about 53 miles), mileage was still a very respectable 49.8 mpg.