Mr. Green Car: 305-horsepower Mustang gets 31 mpg

The 2011 Ford Mustang at the Chicago Auto Show. Photo by Allen Penticoff

By Allen Penticoff
Free-lance Writer

At this year’s Chicago Auto Show, I noticed a Ford Mustang with 31 mpg emblazoned on its flanks. I did not inspect the car as there was a crowd around it, but I did make a mental note that its claim of 305 horsepower and 31 miles per gallon was a remarkable achievement worthy of a Mr. Green Car story.

Indeed, it turns out Ford has made automotive history in creating a performance car with more than 300 horsepower and certified fuel economy greater than 30 mpg. Let’s look at how they accomplished this feat.

The lightweight, all-aluminum, 3.7-liter V-6 is the basis of their new base performance engine. Not only does it have the latest in electronic ignition and direct fuel injection technology that has helped all motor vehicle manufacturers gain performance and economy, but also it has the latest in valve train technology. Ford calls this technology Twin Independent Variable Camshaft Timing (Ti-VCT).

Through computer control, the double-overhead camshafts are independently controlled to optimize valve timing for the best performance and efficiency as demanded by the throttle position, speed and other factors. As an example, the timing will be different when you mash your foot to the floor to get all 305 horsepower than it will be when you let off the gas or are sitting idling at a stoplight.

Valve timing technology is not new; several manufacturers have used it to get more power or efficiency from smaller engines. So Ford is getting onboard with this technology in their pony car.

While Mr. Green Car does not endorse super-powered vehicles, it is worth noting that the Mustang’s 5.0-liter, 32-valve V-8 produces 412 horsepower, yet still attains 26 mpg; the 550-horsepower GT-500 is not driven for fuel economy at all.

It takes more than just an efficient engine to get good gas mileage. Ford’s new six-speed automatic transmission delivers a final gear that keeps the engine revolutions low at highway speeds, but as soon as performance is needed, it drops down a gear or two—and away you go.

Interestingly, the automatic transmission is the one that delivers the 31 mpg rating. Their six-speed manual transmission provides for 30 mpg on the highway.

It was not that long ago that automatic transmissions universally had lower fuel efficiency than manual transmissions, but like many things, this is no longer true. Computer-controlled automatic transmissions can do a better job shifting than you can.

One thing an automatic transmission can’t do—keep you more alert. Studies have shown that drivers with manual transmissions are paying more attention to the road as they drive, thinking ahead as to what their gear needs will be. It’s also kind of fun to shift, and that is why the manual is the standard transmission for the fun Mustang.

Other chassis details aid in increasing fuel economy. The power steering pump is gone, replaced by Electric Power Assist Steering (EPAS). Again, electric power steering is nothing new, but it takes the power using power steering hydraulic pump off the engine where a little power, and, therefore, fuel, was always needed to assist the steering effort. Electric power steering needs little power.

Ford also improved the aerodynamics of the 2011 Mustang with a new front facia, tire spats on the rear wheels, modified underbody shields, taller air dam and an added rear deck seal, according to Ford’s March 4 press release. Oh, and the soybean-based seat upholstery is a nice green touch.

Altogether, all these improvements add up to a car that is fun to drive where and when “getting on it” is appropriate. Mustangs have good handling and styling to be proud of. But you won’t be able to use that 305 horsepower very often—you will benefit more from its 19 mpg city mileage rating by not “getting on it.” Even going slow, they’re great to look at. The Mustang is being built at the AutoAlliance International Plant in Flat Rock, Mich.—you can get one now, starting at $22,145. I recommend the convertible for the most fun while not going so fast.

From the June 2-8, 2010 issue

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