The best way to ensure a return appearance on the Ward's 10 Best Engines list is to substantially improve on what you did the previous year. Ford Motor Co. did that in spades with its hybrid system in the '10 Fusion sedan.

A winner in 2009 when we tested the Escape Hybrid, the system in the Fusion Hybrid boasts mechanical, engineering and software upgrades. The result is better mileage, smoother power transitions from gas to electric assist and the ability to drive faster in all-electric mode.

The Escape Hybrid impressed us last year with 34/31 mpg (6.9-7.5 L/100 km) city/highway, numbers we easily exceeded during testing. The Fusion Hybrid offers an even better rating, 41/36 mpg (5.7-6.5 L/100 km). We also easily beat those in real-world driving, averaging 55.2 mpg (4.3 L/100 km) at one point.

Both vehicles use the same 2.5L DOHC I-4 operating on the Atkinson combustion cycle, but the Fusion makes 156 hp vs. 153 hp in the Escape.

The torque peak of 136 lb.-ft. (184 Nm) arrives much earlier in the Fusion as well: 2,250 rpm compared with 4,500 rpm in the Escape.

Total system power goes up too: 191 hp instead of 177 hp in the Escape, even though the electric motor is smaller (275 volts vs. 330 volts).

Ford says the system upgrades allow the Fusion Hybrid to operate longer at higher speeds in electric mode, up to 47 mph (76 km/h). That's about 7 mph (11 km/h) faster than the CUV. Some editors managed 40 mph (64 km/h) in EV mode.

Judges also noted the interaction of internal-combustion and electric-power sources was even more seamless.

The new Fusion features the next-generation transaxle with a downsized traction motor and generator, plus the addition of a variable voltage controller that allows the electric motor output to hit 160% of rated power.

Credit also goes to Ford's aggressive use of engine braking, instead of foundation brakes, to initially — and smoothly — slow the vehicle during deceleration.

This technical tweak, combined with the ability to stop the engine during deceleration and start it up again during acceleration so effortlessly the driver does not even notice, led to high marks in the noise, vibration and harshness department.

Because they are designed to be HEVs and not plug-in electrics, both the CUV and the sedan only can drive about 1 mile (1.6 km) under full electric power.

But that's plenty of time to deliver a unique and addictive driving experience, something we never, ever, thought we'd find in an HEV.


Engine type: 2.5L DOHC I-4 Hybrid

Displacement (cc): 2,488

Block/head material: aluminum/aluminum

Bore × stroke (mm): 89 × 100

Horsepower (SAE certified): 156 @ 6,000 rpm

Torque: 136 lb.-ft. (184 Nm) @ 2,250 rpm

Specific output: 62 hp/L

Compression ratio: 12.3:1

Electric motor: 275-volt, 106 hp @ 6,500 rpm

Total system power: 191 hp

Assembly site: Chihuahua, Mexico

Application tested: '10 Ford Fusion Hybrid

EPA city/highway (mpg): 41/36