Plug-in hybrid vehicles that are frequently recharged from electric mains and seldom operate on gasoline power can run for hundreds of miles per-gallon; however, “rechargeable batteries tend to die much faster if they are constantly discharged until empty,” according to ABI Research senior analyst Dan Benjamin.

Owners have been known to modify their hybrid vehicles to run longer solely on electric power, though it would probably void their warranty, Benjamin said. “Factory hybrid systems will use the conventional engine to charge the battery before it discharges too much, but plug-in hybrids are specifically intended to run longer on battery power, and will thus result in higher rates of battery failure."

“When automakers experimented with pure electric vehicles, the batteries were intended to be replaced every few years,” Benjamin noted, “but to be cost-practical, batteries in hybrids are intended to last for the life of the vehicle. Replacements are expensive, and automakers would not want to pay for this cost as part of a warranty.”

Benjamin predicted “something of a market for plug-ins on the commercial side,” in Europe and Asia where there is already more interest in pure electric vehicles. “Eventually we could see the technology offered on a passenger vehicle, though not any time soon," he said.