A plug-in hybrid has a larger battery than a regular hybrid and a charging port. Charge it at home and the first 20 to 50 miles of driving can be all electric. After that, it behaves like a conventional hybrid, burning gasoline and using regenerative braking.

The Chevrolet Volt, launched in 2010, popularized the idea. Its gasoline engine served mainly as a generator when the battery ran low. Other makers, from Toyota to Volvo, built plug-ins that blend engine and motor power more directly. The category sits between hybrid and battery electric, and it appeals to drivers who want electric commuting without range anxiety.

Why plug-in hybrids exist

• Most daily trips fit within the electric range.
• Long road trips use gasoline, no charging stops needed.
• Tax incentives in many countries reduce the purchase price.
• They can qualify for carpool lane access in some regions.

The catch is that a plug-in hybrid only saves fuel if you actually plug it in. Drive one without charging and it becomes a heavier, less efficient hybrid. Fleet data suggests many company plug-ins never see a charger. Buyers who commit to nightly charging get the most out of the design.