NATURAL GAS SALES: Ford sold a record 11,600 trucks and vans powered by natural gas in 2012. Other companies are also seeing gains.

WHY THEY'RE RISING: Unlike gasoline and diesel prices, which have risen more than 30 percent since 2007, natural gas prices are low thanks to a spike in production. Companies and cities are buying natural gas trucks in big numbers, betting prices will stay low.

IN MY GARAGE? Honda sells the only natural gas car on the market right now, and home fueling stations are expensive. But analysts say that could change in the next few years.