Cars.com Hybrid Mileage Challenge: Part 2

Yesterday, we introduced the four fuel-sippers — a Chevrolet Tahoe Hybrid, Ford Escape Hybrid, Honda Civic Hybrid and Toyota Prius — we schlepped through Chicago traffic early this month. We took pains to drive as we normally would: No nursing the gas pedal to stay in electric mode or purposely coasting to regenerate more braking energy. Just ordinary stop-and-go driving. Faced with some wonky fill-up numbers at a gas pump on the fritz, we took our results from each vehicle’s onboard mileage readout, which we reset at the beginning of each new leg. Read below for the numbers, along with some postgame analysis.

Thanks to their electric-only modes, the Escape Hybrid and Prius achieve their highest mileage ratings in city driving, and both handily outperformed EPA estimates. The Chevy Tahoe Hybrid stayed right on the money. The Civic Hybrid has more traditional mileage estimates — like most cars, it does best on the highway — but our mileage came up a bit short of the car’s 40-mpg city estimate. (We rotated drivers for each leg, so driving style can’t be to blame.)

How did the Civic do so poorly? Perhaps our A/C usage (see Part 1) had something to do with it, though the latest EPA mileage estimates purportedly account for some A/C usage. Honda spokesman Jon Fitzsimmons said using the Civic Hybrid’s high-efficiency A/C can lower mileage. He didn’t specify how much, but the University of West Virginia’s James Smith said most conventional A/C systems hurt fuel efficiency by two or three mpg. Smith teaches mechanical and aerospace engineering, and he’s also the 2009 president-elect for the Society of Automotive Engineers.

It’s hard to judge the effect of the remaining variables. Carrying a passenger — necessary for photography — had limited effects: The Escape and Civic hybrids managed their best mileage with the extra weight, while the Tahoe Hybrid and Prius yielded middling results. The day’s heaviest traffic took a toll on all but the Escape Hybrid, which generally thrived in congestion. Expectedly, the Civic Hybrid did better on the faster sections in the evening, while the Prius was the reigning fuel-sipper all morning. The Tahoe Hybrid proved unflappable — no matter the traffic, temperature or passenger load, its MPG readout stayed right around its EPA-estimated 20 mpg.

In the end, the day’s top honors went to the Prius. In stark contrast to our 34 mpg results a year and a half ago, this one posted 17% better city mileage than its revised EPA ratings. In fact, our results come within spitting distance of the Prius’ pre-2008 60 mpg city rating. The Escape Hybrid proved similarly impressive, with 13% better mileage than its 34 mpg city rating. The Tahoe Hybrid didn’t wow us with efficiency, but its consistency deserves merit. The Civic Hybrid was comparatively unimpressive, though we suspect that had the A/C stayed off, the results might have been a couple mpg better.

Stay tuned for some impressions of how each hybrid drove and conveyed mileage information, as well as some insight on how in-car mpg readouts work.