2010 Honda Insight is another mileage champ that’s not much fun to drive.

I recently spent a few weeks with our magazine’s long-term Volkswagen Jetta TDI, which has earned a lot of respect around the office but which I was less than thrilled with. Although I often saw an indicated fuel economy as high as 40 mpg without really trying, annoyances like a fussy engine/clutch interface, an overly soft suspension, and noisy acceleration bleed the joy of driving it. Immediately after the Jetta, I got a Honda Insight, and that was still more economical but even less fun to drive.

Commendably, the Insight sipped fuel even more slowly than the Jetta, downing a gallon of regular every 40 to 45 miles, according to the dashboard readout. I liked the big digital speedometer, which glows green when you’re driving economically and blue when you’re not; there’s also a gauge in the cluster which essentially tells you the same thing. The interior imparts a feeling of spaciousness; even the back seat is okay, but getting in can be hazardous—my nine-year-old bonked his head, and he’s all of five feet tall. The cloth upholstery in the EX is nicer than the norm (and leather also is available, for those whose concern for the earth does not extend to bovines); but interior surfaces, although cloth-covered, are universally hard to the touch. The cargo hold is fairly large, and the two-pane glass hatch—just like that in a Prius, or an old Honda CRX—provides a reasonable (although bisected) view out the back.

Much has been made of the Insight’s Toyota Prius-undercutting sticker price, which ranges from $20,510 (LX) to $23,810 (EX with navigation). But the Insight feels every bit like an economy car, because—aside from its hybrid-specific equipment—it’s outfitted about as well as a $6000 cheaper Honda Fit. Dynamic disappointments include a harsh ride on the basic, beam-axle rear suspension, and acceleration that is slow and noisy, an impression exaggerated by the continuously variable transmission. Oddly, under low-speed, light-throttle acceleration, the Fit would often chug-chug-chug ahead in a weird surging pattern that I’ve never experienced in any other hybrid.

So, the Insight, even more so than the Jetta diesel, proves that’s there’s no painless road to super-high mileage. (Only the Ford Fusion hybrid, EPA rated at 39 mpg combined, has relatively few dynamic shortfalls compared to its conventionally powered sibling; but it is significantly more expensive, commanding an $8000 premium over a standard four-cylinder Fusion.) In the next few weeks I’ll be giving the redesigned Toyota Prius a try, so we’ll see how that goes.

But the good news is that achieving that last measure of extreme frugality may not be so important anyway. Although it’s counterintuitive, the real-world difference between 30 mpg and 40 mpg, for instance, is nowhere near as great as the difference between 15 mpg and 25 mpg. If you look at gallons used to drive a set distance—a figure that is readily available at the EPA’s fueleconomy.gov web site—you can see it. So if you’re trading in a vehicle that gets bad gas mileage, even a new car that’s only moderately economical will make a big impact, while stretching for an extreme econo-miser won’t help that much more. And certainly there are a lot more 25-mpg cars that you’d want to drive every day than there are 40-mpg cars about which you can say the same.