Years ago, before the Toyota Prius earned respect in the market and while gasoline remained cheap, the debate was spirited among Ward's editors deciding whether the hybrid-electric vehicle even belonged on the 10 Best Engines list.
The naysayers since have been silenced, vanquished by the runaway success of the Prius, which still managed nearly 130,000 U.S. sales through November in an awful market, according to Ward's data.
This year, there was no debate about the all-new, third-generation Prius' rightful place on the list. The marketplace has recognized the remarkable fuel efficiency the 1.8L DOHC I-4 hybrid can deliver when coupled with an electric motor, and so must we. The Prius also earned 10 Best Engines honors in 2001 and 2004.
A full hybrid since its introduction in 2000, the new Prius benefits from a larger, more powerful 1.8L Atkinson-cycle, 4-cyl. that produces 98 hp. Combined with the electric motor, the new hybrid system generates a net 134 hp — 24 hp more than the previous car.
An electric water pump and new exhaust-gas recirculation system adds to the engine's efficiency.
Toyota also delivers a clean-sheet overhaul of its patented Hybrid Synergy Drive technology that includes a lighter transaxle, a new direct cooling system for the inverter and new, more sophisticated regenerative braking system that feels much less grabby than previous generations.
Throttle tip-in is surprisingly smooth, and the power surges Ward's editors used to notice on the highway are gone. The continuously variable transmission operates smoothly, and the transition from gas to electric and vice versa is seamless. At stop lights, the engine starts back up without a whiff of hesitation.
There are four ways to drive the Prius. Without changing any settings, the driver will be in the standard (or default) mode, which provides decent acceleration and pretty good mileage, too. Three other modes can be selected with switches on the center console.
Hyper-milers will want the most aggressive “EV” setting, which doesn't last long before the gas engine switches on, even with a light foot.
Slightly more enjoyable (but less fuel efficient than EV) is “ECO” mode, which stiffens accelerator-pedal resistance and makes it more difficult to tip into the throttle.
TOYOTA MOTOR CORP.: 1.8L DOHC I-4 HYBRID
Engine type: 1.8L DOHC I-4 Hybrid
Displacement (cc): 1,798
Block/head material: aluminum/aluminum
Bore × stroke (mm): 80.5 × 88.3
Horsepower (SAE net): 98 @ 5,200 rpm
Torque: 105 lb.-ft. (142 Nm) @ 4,000 rpm
Specific output: 54 hp/L
Compression ratio: 13.0:1
Electric motor: 650-volt max, 80 hp
Total system power: 134 hp
Assembly site: Tsutsumi, Toyota City
Application tested: '10 Toyota Prius
EPA city/highway (mpg): 51/48