It’s a pretty simple formula. Want a car that burns less gas? Then limit the number of cylinders in the engine. From four down to three? Well, in theory that was a good way to build a high MPG car a couple of decades ago but in practice it didn’t work so well. The problem was execution. The 3 cylinder cars of the 1980s, such as the Geo Metro, Subaru Justy and Daihatsu Charade were quite thrifty but rather unrefined.
The engines in those cars weren’t balanced terribly well because of basic physics. Because two of the pistons move up and down in the cylinders at the same time, a three-cylinder engine is naturally unbalanced. Plus, these three bangers delivered painfully low performance. Here’s an example: the 1.0-liter engine in the Charade, sold here in the states from 1988 to 1992, generated just 53 hp and needed a full 15 seconds to propel the 2,000-pound compact hatchback to 60 mph. Perhaps it’s only strong suit: a respectable 38 mpg highway EPA fuel economy rating.
The 2014 Ford Fiesta SFE, by comparison, shows how today’s technology has transformed the three-cylinder engine. The laws of physics still remain but engineers have developed work arounds. The Fiesta SFE has the same size engine as the Charade had, 1.0-liter, but it is rated at 123 hp, over twice that of the Charade. It carries an EPA rating of 45 mpg on the highway and can move the Fiesta — which weighs 800 pounds more than the Charade — to 60 mph in less than 8 seconds.
Automakers are turning to threes for a number of reasons: Smaller engines reduce vehicle weight, which improves handling and braking. Also, three-cylinder engines use roughly 20 fewer parts than four-cylinders and are thus cheaper to build. And, because the engines are so compact, they can help improve safety in front-end crashes. This is because with more space around the smaller engine, the chances of it penetrating the interior in a severe high-speed crash are reduced. But most important, three-cylinder engines can deliver diesel-like levels of fuel economy for much lower cost.
What is not yet known is how consumers will accept the modern three-cylinder. Ford, BMW and other automakers are not drawing attention to the number of cylinders. That’s due in part to the reputation of older three-cylinder engines. Instead, their message focuses on performance and fuel economy. Wade Jackson, the Fiesta brand manager at Ford, says no promotions are planned to point out that the Fiesta SFE has a three-cylinder engine. The focus instead is on gas mileage. With the Mirage, Mitsubishi’s focus was purely economic; delivering an affordable entry-level car that offers the fuel economy of a diesel or a hybrid, but at a much lower price. The goal was to reduce the vehicle’s overall curb weight to enable the engine to deliver adequate performance. The Mirage weighs just 1,863 pounds and can reach 60 mph in about 11 seconds.
Courtesy of : Ford Dodge Ford Lincoln Toyota