Many analysts have predicted that the rising cost of gas would encourage many drivers to opt for more fuel-efficient vehicles, and General Motors' recent sales estimates seem to have proven them right. The automaker says that March was its best month of high mile-per-gallon cars in its lengthy history.

To qualify as a high-MPG ride, GM said the car has to get 30 miles to the gallon or more. The company said that it sold 100,000 such products during March, a figure much higher than in previous years. In fact, the amount of fuel-efficient vehicles has spiked significantly since as recently as 2009.

"Three years ago, about 16 percent of the vehicles GM sold achieved at least 30 mpg on the highway," said Mark Reuss, president of GM North America, in a statement. "Today, that number is about 40 percent and we have more new fuel-economy leaders on the way, including the Chevrolet Spark, Cadillac ATS and Buick Encore."

GM currently offers 12 cars that fit the bill. The top-ranking vehicle is the electric Chevrolet Volt, which gets the equivalent of 93 miles per gallon, but for those not sold electric vehicles just yet, other options including the Chevrolet Sonic, Buick Verano and GMC Terrain all eclipse the 30 MPG mark.

Although this year's fleet of GM cars are particularly fuel-efficient, there are plenty of used options available that can save you just as much money at the pump. In particular, New Jersey State Auto Auction has a wide variety of makes and models at affordable prices, whether you're looking for a fuel-efficient used Chevrolet or a powerful SUV.