Ford Motor Co.: 2.5L DOHC I-4 HEV
By Tom Murphy WardsAuto.com, Dec 19, 2008 8:59 AM

Placing a hybrid-electric vehicle on the 10 Best Engines list is always a charged affair.

Only three auto makers have managed to crack the list this decade, amid questions from internal-combustion purists who want this competition to be only about engines, not tag-team systems that need electric motors.

This year, a fourth OEM joins that short list as Ford Motor Co. collects a trophy for its second-generation Escape Hybrid cross/utility vehicle, which benefits in no small measure from Ford’s all-new 2.5L DOHC I-4. The engine replaces the less capable 2.3L I-4 in the first-generation HEV.

With intake variable camshaft timing, the new 4-cyl. delivers a broader power band and operates on the Atkinson combustion cycle (similar to most other hybrids), which improves efficiency up to 10% over conventional Otto-cycle configurations by keeping the intake valves open longer.

This reduces the engine’s pumping losses by allowing a small portion of the fuel/air charge to flow back into the intake.

Mechanical changes include new intake and exhaust manifolds; a new intake camshaft; and higher-compression pistons (12.3:1) vs. the non-hybrid I-4 (9.7:1). The previous generation’s nickel-metal-hydride battery, continuously variable transmission and electric motor carry over to the new hybrid.

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Most of these changes are indiscernible to the driver, but a smart new engine controller allows the driver to rapidly identify the considerable gains achieved by the new Escape Hybrid.

The new processor allows for smoother transitions between gas and electric mode and more EV-mode driving. The old Escape Hybrid might make it to 30 mph (48 km/h) on electricity, alone, but tuning refinements enable the new 5-passenger CUV to hit 40 mph (64 km/h) without consuming a drop of gasoline.

The same hybrid configuration also is available in the Escape’s platform mate, the Mercury Mariner.

Make no mistake, the Escape Hybrid is not a “performance hybrid” with whopping torque and high horsepower. Instead, this vehicle is all about great fuel economy.

We’ve tested too many hybrids that have failed to meet their federal mileage expectations, but not the new front-wheel-drive Escape Hybrid, which is rated at 34/31 mpg city/highway (6.9-7.5 L/100 km).

Even without extreme “hyper-mile” driving tactics, meeting and surpassing those numbers is not difficult. One Ward’s judge managed 39 mpg (6 L/100 km) in a mixed driving cycle and a staggering 46 mpg (5.1 L/100 km) in mostly city driving, without inciting road rage among other motorists who prefer to be ahead of poky drivers.

General Motors Corp.’s 2-mode hybrid in the GMC Yukon earned a 10 Best Engines award in 2008, but this year’s standard-bearer among hybrids is the ’09 Escape, which is about half the price and capable of twice the fuel economy, while still being a remarkably roomy and functional CUV.

tmurphy@wardsauto.com

Ward’s 10 Best Engines is a copyright of Penton Media Inc. Commercial references to the program and/or awards are prohibited without prior permission of Ward’s Automotive Group.