More often than not, buyers of all-wheel-drive cars and SUVs must deal with worse gas mileage compared with their two-wheel-drive counterparts. The 2011 Audi TT now only comes with all-wheel drive — a front-wheel-drive option was eliminated for 2010 — but its gas mileage is still respectable at 22/31 mpg city/highway. Along with the TT, we put all-wheel-drive versions of the 2011 Chevrolet Equinox with its four-cylinder base engine and 2011 Dodge Charger R/T with a healthy V-8 through our heavy Chicago commute.
 
The TT makes an interesting case as a commuter car.

Achieving 25.2 mpg after a brutal commute is impressive for a fun-to-drive all-wheel-drive sports car. Unfortunately, its stiffly sprung suspension wore on my back. Smoother roads or a shorter drive could make its case as a commuter car for those looking for a little sport without sacrificing mileage. The TT does require premium fuel, though. 
 
In our previous testing, the Equinox with front-wheel drive couldn’t back up its 32 mpg highway rating. With all-wheel drive and a slow commute, it came up short of its 20 mpg city rating, at 17.1 mpg. However, the Equinox’s commute had a lower average speed than most of our drives. Still, we're not impressed with the results.
 
Although the 2012 Charger V-6 gets an eight-speed automatic transmission to bump gas mileage up to 31 mpg on the highway, the V-8-powered R/T continues with its five-speed automatic like the one I tested. With this configuration, plus all-wheel drive, the Charger managed 17.3 mpg on my commute. 
 
Extreme commuting is defined by the U.S. Census Bureau as someone who spends more than 90 minutes per day on the way to the office. Since Cars.com is based in downtown Chicago, our commutes last that long and can bring out the worst — or best— gas mileage in the cars we test. We wanted to give an idea of what to expect in these conditions by tracking our gas mileage.
 
My real-world commute averages 35 miles one way from the western suburbs to downtown Chicago. It takes 90 minutes on good days and up to three hours on bad days. Those are really bad days. Speeds average 22 to 25 mph.

Like in our mileage challenges, data is collected from the car’s on-board trip computer. As we've reported before, they are generally accurate, especially when calculating trips of this length.

2011 Audi TT coupe, all-wheel drive

• 2.0-liter turbocharged four-cylinder, six-speed dual-clutch automatic transmission
• EPA rating (city/highway/combined): 22/31/26 mpg
• Time: 1 hour, 29 minutes
• Trip mpg: 25.2 mpg
• Trip miles: 34.3 miles
• Average speed: 25.2 mph
• Outside temp: 60 degrees

2011 Chevrolet Equinox, all-wheel drive

• 2.4-liter four-cylinder, six-speed-automatic transmission
• EPA rating (city/highway/combined): 20/29/23 mpg
• Time: 1 hour, 38 minutes
• Trip mpg: 17.1 mpg
• Trip miles: 33.7 miles
• Average speed: 20.6 mph
• Outside temperature: 93 degrees
  

2011 Dodge Charger R/T, all-wheel drive

• 5.7-liter eight-cylinder, five-speed-automatic transmission
• EPA rating (city/highway/combined): 15/23/18 mpg
• Time: 1 hour, 24 minutes
• Trip mpg: 17.3 mpg
• Trip miles: 32.9 miles
• Average speed: 23 mph
• Outside temp: 87 degrees