The current work horse of the cab fleet, the Ford Crown Victoria, is rated at 17 miles per gallon in city driving. The hybrid Escape (apparently, the favorite hybrid for taxi fleets because of its interior room) is rated at 36 in the city. Even if those numbers don't hold up in real-world driving, the Escape is going to use about half as much gas as the Crown Vic. And a hybrid Prius (not as roomy as most cabs, but I'm sure it gets the job done) would save even more.

The especially nice thing is that cabbies can serve as a proof of concept for the longevity of hybrids.

Some potential hybrid buyers -- cab fleets included -- are worried about how long the hybrid batteries will last. Replacing a hybrid's batteries can be pretty costly, so the sooner they fail, the more expensive it is to own a hybrid over the long run. But from an admittedly small sample of hybrid taxis in service in Canada, it seems that even the early models could run for more than 332,000 km (200,000 miles) with no battery problems. In fact, the hybrid taxis experienced no wear-and-tear problems with the hybrid parts themselves -- the only parts that wore out were the ones common to all cars.

Based on the experience of the early taxi adopters, then, the batteries seem pretty reliable. Which should give some comfort not just to cabbies, but to anyone who's already bought, or is considering switching to, a hybrid.