A recent flap briefly roiled the small but growing market for the 2011 Chevrolet Volt plug-in hybrid. A critic of tax support for hybrid and electric vehicles raised allegations — so far unproven — that some car dealers have been selling low-mileage used models of the Chevy Volt without making it clear that the much-ballyhooed $7,500 tax credit no longer applied.While it might have been a tempest in a plug-in-hybrid teapot, the incident raised questions about the limited familiarity that consumers have with the rules of rebates and tax credits for the new generation of electric-drive and alternative-fuel vehicles.

That's understandable. The rules are complex, and once someone hears about a tax credit for a particular type of car, it is pretty easy to assume that all cars like it will qualify.

A good car dealer should let consumers know right away which models in its showrooms qualify for various federal, state and regional tax credits and rebates. But what's good and right and what actually gets done are often different things. The smart consumer should go shopping for an advanced-technology vehicle fully armed with information, and shouldn't depend on what a dealership might or might not say.

Can't Pass Them On
In the case of the used Volts, the answer is pretty simple: Only the original buyer can claim the federal tax credit for an electric-drive vehicle. Even if the original buyer/registered owner for some reason doesn't apply, the credit cannot be passed along to a subsequent buyer.