Manual Transmissions Not Always the Most Gas Friendly

Choosing a car for the best fuel economy used to mean looking for a car with a manual transmission, but now many automatics have mileage ratings that are equal to — or better than — manuals. This is good news for consumers because most drivers choose automatics.

Today, five- or six-speed automatic transmissions are the norm, and a transmission with more gears — or "speeds" — offers greater efficiency. There are also continuously variable automatic transmissions, which theoretically have an infinite number of speeds to raise efficiency.

Examples of this include the 2010 Ford Fusion with a six-speed automatic, which has better EPA mileage ratings than its manual transmission version. An automatic Fusion S is rated at 23/34 mpg city/highway, and the manual is rated at 22/31 mpg.

Why the switch? According to Craig Renneker, Ford's chief engineer of automatic transmissions, it's because of a combination of transmission efficiency, computer control, EPA testing and customer behavior.

Traditionally, manual transmissions have been the most efficient because of their minimal internal drag. Today, Ford has produced a six-speed automatic with lower internal drag than some four- or five-speed automatics, Renneker said.

The EPA's ratings have become a good indicator of gas mileage — especially after 2008 when they revisited their testing procedures — and automakers go to great lengths to simulate real-world driving when performing EPA testing.

"Our EPA test procedure for manuals involves taking surveys of actual customers and averaging them into a shift schedule to be used on the test," Renneker said. "As the EPA test requires hundreds of shifts, customer shifting behavior is very significant in the outcome."

An automatic transmission also has the help of a computer that constantly monitors driving habits and can adjust shifts for maximum efficiency. With a manual, driving efficiently is a chore left to the driver.

Another example of an automatic transmission besting a manual is the Subaru Outback with a CVT. For 2010, a CVT-equipped Outback 2.5i is rated at 22/29 mpg compared to 20/26 mpg of the 2009 Outback with a four-speed automatic.

The CVT transmission's ability to maintain optimal engine speed during acceleration is the main reason for the Outback's gas mileage improvement, said Dominick Infante, Subaru's spokesman. For the 2010 model, the automatic surpasses the manual's rating of 19/27 mpg.

For many years, Nissan has been using CVTs on its models ranging from the Murano crossover SUV to its recently introduced Cube. When equipped with a CVT, the 2009 Cube's 28/30 mpg bests the manual's 24/29 mpg.

Here are some 2010 automatic cars that get better estimated mileage ratings than their manual counterparts.

Automatic vs. Manual
Cars are listed below with their engines, transmissions and EPA-estimated mileage figures. If a car has a base four-cylinder engine and an optional four-cylinder, the engine's liter size was added to differentiate between the offerings. Transmissions are outlined: A5, A6 = five-speed automatic, six-speed automatic; M6 = six-speed manual; CVT = continuously variable automatic transmission
2010 Chevrolet Camaro
V-6 A6: 18/29 V-6 M6: 17/29
V-8 A6: 16/25 V-8 M6: 16/24
2010 Ford Fusion
4-cylinder A6: 23/34
4-cylinder M6: 22/31
2010 Hyundai Genesis Coupe
V-6 A6: 17/27
V-6 M6: 17/26
2010 Kia Forte
2.0-liter, 4-cylinder A5: 27/36
2.0-liter, 4-cylinder A4: 25/34
2.0 4-cylinder M5: 25/34
2.4-liter, 4-cylinder A5: 23/31
2.4-liter, 4-cylinder M6: 22/32
2010 Mazda3
2.5-liter, 4-cylinder A5: 22/29
2.5-liter, 4-cylinder M6: 21/29
2010 Mercury Milan
4-cylinder A6: 23/34
4-cylinder M6: 22/31
2010 Mitsubishi Lancer Sportback
4-cylinder CVT: 21/27
4-cylinder M5: 20/27
2010 Subaru Legacy
4-cylinder CVT: 23/31
4-cylinder M6: 19/27
2010 Subaru Outback
4-cylinder CVT: 22/29
4-cylinder M6: 19/27
2010 Volkswagen Golf
Diesel 4-cylinder A6: 30/42
Diesel 4-cylinder M6: 30/41
4-cylinder A6: 23/30
4-cylinder M5: 22/30
2010 Volkswagen GTI
4-cylinder A6: 24/32
4-cylinder M6: 21/31
© Cars.com 10/5/09