LOS ANGELES (Reuters) - Call it an economic and environmental murder mystery in the making: Will a cash-strapped Detroit kill the electric car -- again?

Stung by an association with gas-guzzling SUVs and pushed to the brink of failure by plunging sales, U.S. automakers have been touting efforts to roll out more fuel-efficient small cars, gas-saving technology and gas-free electric vehicles.

The star of that marketing show has been the Chevy Volt, a rechargeable car that General Motors Corp is designing to run 40 miles on battery power, meaning some commuters would never need to fill up with gas.

But with its cash dwindling and U.S. auto sales crashing to 25-year lows, GM has joined Ford Motor Co and Chrysler LLC in seeking $25 billion in federal handouts, which are under consideration this week by the U.S. Congress.