I conducted a little, informal experiment in our Prius last weekend. On a trip north to visit family in Vermont, a distance of almost exactly 300 miles each way, I drove up going no faster than the posted 65-mph speed limit. I also did without air conditioning in spite of 80-degree temperatures outside. Thanks to the plentiful use of glass in the Prius cabin design, inside temperatures were considerably higher. (How we suffer for science...) At least, for the sake of humankind and my marriage, I was traveling alone.

As for driving style, I drove smoothly using cruise control, keeping the speed consistent even on hills. Driving 65 on the highway gives you plenty enough opportunities to get rear-ended these days; you won’t catch me hypermiling at 45 mph up the hills. 

The results? 50-mpg.

Coming home, temperatures were about the same, and I indulged myself with A/C. I also stepped it up to a 70-mph cruise, still below the speed of most fellow travelers, but fast enough to reduce the frequency of close encounters of the Kenworth kind. This time, the Prius and I managed 49-mpg, and we both arrived minty-fresh.

Give me the A/C and the extra 5 mph, thanks. I’ll make do with 49 mpg in comfort.

—Jim Travers