Looking forward to a four-cylinder truck to fix your fuel economy woes? Well, Car and Driver's latest testing might set that plan back just a touch.

The magazine's editors slid behind the wheel of the new Silverado 1500 equipped with the 2.7L turbo-four to put its fuel economy figures to the fire. We've already talked about the truck's EPA figures. And how at 20 mpg city, 22 highway it matched the 5.3L V8 on the highway. But GM execs have also talked about how it would perform better in the real world.

So Car and Driver took the 2.7L-equipped RST Double Cab they had to review and put it through their own 75 mph highway test. Then compared it with the same test in an RST-equipped Crew Cab with the 5.3L V8. Both 4x4, 8-speed auto trucks.

The results: 18 mpg for the 2.7 on the 200 mile test. 14 percent less than the 21 mpg they got in the 5.3L truck.

How? It's a high-speed test, unlike the EPA cycle's 48 mph plus occasional higher-speeds test. The Silverado is still a big brick through the air. The 5.3 also gets GM's fancy dynamic fuel management that lets it run on as few as just one cylinder. The 18 mpg test also tied the Sierra 1500 Denali they tested, with the 6.2L V8 and the 10-speed auto.

We'll wait and see how the upcoming diesel fares, and how the 2.7T does for fuel economy in the city.

Car and Driver