The price of gas has climbed to $3.93 a gallon, on average, from $3.76 a month ago. And that weighed heavily on car buyers' minds in March.

Shoppers turned their focus to smaller and more fuel-efficient vehicles, hoping to get some relief at the pump.

General Motors (GM) has 12 vehicles that do at least 30 mpg on the highway, and each of those was a sales winner in March. Combined, those 12 models contributed to 100,000 in sales for the month -- a record for GM.

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Three years ago, only 16% of GM's sales were at that threshold of at least 30 mpg. Now, the company said, it's 40%. Those fuel-efficient vehicles include the latest versions of the Chevy Cruze, Chevy Malibu, Buick Verano and Chevrolet Sonic.

GM and the other major automakers will release their March sales totals Tuesday. Analysts are expecting sales strong enough to give the industry the best quarter in four years.

Reuters reports that 34 analysts surveyed think March sales will reach an annualized rate of 14.75 million vehicles. That's a huge improvement from the last few years, when the spiraling economy led many drivers to put off new-car purchases. The annualized rate was only 13.3 million a year ago, and auto sales dropped to 10.4 million in 2009.

"Vehicle trade-in rates have achieved sustained highs in recent months, which suggests that consumers have decided that they've held on to their cars for too long," Jessica Caldwell, an analyst with car site Edmunds.com, told Reuters.

Automakers are also more accepting of buyers who might not have the best credit. Caldwell said the average credit score for buyers is at its lowest level since the first half of 2008.

Shares of GM rose more than 3% Monday morning to $26.50.

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