It is if you're running the numbers on an SUV, such as the GMC Acadia, which gets those mileage figures. Compare the Acadia to one of its stablemates, the GMC Yukon. Both SUVs have roughly the same amount of interior space for hauling things around, but the Yukon is the thirstier of the bunch -- it comes 'round the gas station more often, because it only gets 14 mpg in city driving, and a mere 19 mpg on the highway.

Big deal, you might say. So what's two miles per gallon in the city, anyway? They can't match a Civic Hybrid or even a Chevy Aveo in mileage. And even if you use a combined figure (averaging out city and highway mileage), there's still only a three-miles-per-gallon difference between the two vehicles.

Let's approach this from another angle: In a typical year's worth of driving, using 15,000 miles as an example, someone who drives an Acadia will consume 148 gallons less fuel than someone who drives a Yukon.

Now let's compare another set of cars -- say, a Nissan Altima, which comes in both regular and hybrid versions. A regular gas-engined Altima gets 26 mpg, and the hybrid version gets 34 mpg. That's a difference of eight miles per gallon. Surely that makes more of a difference than the paltry three miles per gallon difference of the large SUVs we mentioned, doesn't it?

Not if you factor in the amount of fuel used. If we use the same 15,000 miles per year traveled that we used in calculating the fuel usage of the SUVs, we find that by buying a Nissan Altima Hybrid, we'd only have saved 136 gallons of fuel a year over its non-hybrid variant.

True, the smaller cars save fuel in the long run, when compared with a large truck or SUV. But buyers of large trucks may need the large vehicles for specific purposes, and not just to look good while carrying the kids around town -- so they may never be in the market for a small vehicle. After all, if you've got a bunch of kids, two dogs, and you live where there's a couple of feet of snow in the winter, chances are you're going to go for the SUV and not a tiny little runabout.

Therefore, upcoming vehicles such as the Dodge Durango Hybrid or the GMC Yukon Hybrid (pictured), both due out this fall, will make an impact, because they will save fuel that otherwise would be guzzled by another large vehicle.