Hybrid cars keep improving, so when do you buy?

— -- Car buyers trying to cut gas costs face a tough choice regarding hybrids: Buy now, or wait for a more capable and potentially cheaper next-generation car?

"Buy now," says Bradley Berman, editor of HybridCars.com. "There's so much talk about what's around the corner. You can't believe it until the goods are delivered."

Carmakers would not argue. The industry's June sales are due out Tuesday, and they are expected to show another big drop. Hybrids are one of the few hot categories, and the automakers would be happy for them to keep selling as soon as they hit the lot.

But automakers also are pushing hard to build more capability at less cost into their next generation of hybrids.

"We signed off on our first hybrid application with Mercedes, and literally the next meeting was about, 'How are we going to get costs out?' " recalls Mary Ann Wright, vice president of Johnson Controls' hybrid battery business.

The next generation of gas-electric hybrid technology looks to be:

•Cheaper. Honda and Toyota say they are seeking to dramatically cut hybrid-manufacturing costs, raising hope for consumer savings.

Honda Motor says a new hybrid hatchback for the USA next year should show a drop in the price premium.

CEO Takeo Fukui said last month in Japan that Honda wants to cut 33%, or about $900, out of the extra cost of a Civic hybrid over the conventional model, so "customers can choose hybrid purely for economical merits."

Likewise, Toyota Motor President Katsuaki Watanabe said in Detroit earlier this year that as the automaker plans more and updated hybrid versions of its vehicles, it is "working very hard to reduce the size, cost and weight by half."

A new Prius is due out next year.

•Smaller. General Motors plans to switch some 2010 hybrids to a new type of battery that is smaller and lighter, yet puts out more juice, CEO Rick Wagoner has said.

Today, GM uses nickel metal hydride batteries in hybrids such as Saturn's Vue.

Coming lithium-ion batteries will shrink the battery pack from the size of a suitcase to about the size of a 12-pack of soft drinks, says spokesman Brian Corbett. Meanwhile, it will have up to three times more power, boosting gas mileage about 20%.

•More capable. Ford Motor says the 2009 Ford Escape Hybrid on sale next month and Ford Fusion and Mercury Milan hybrids due in 2010 will be able to run on electric power alone up to 40 mph — 10 mph faster than current models. As now, when the battery runs down, the gas engine kicks in and recharges it.

Despite such improvements, one expert advises holding out even longer — for hybrids still a few years away that can be recharged from wall sockets and will make short trips on electric power alone.

An example is the Chevy Volt, which GM hopes to start producing sometime in 2010.

Says Sherry Boschert, vice president of advocacy group Plug In America and author of Plug-In Hybrids: The Cars That Will Recharge America: "No plug, no deal."