gas prices
Justin Sullivan/Getty Images

If you filled up your gas tank in the past few weeks, you likely noticed that it isn't costing as much. According to the AAA Daily Fuel Gauge Report, the national average price for a gallon of regular gasoline is $3.35. This is down from $3.40 a week ago and $3.58 a month ago.

In addition to saving drivers money at the pump, the lower gas prices are fueling sales of less fuel-efficient vehicles. USA Today reports that "the 'window-sticker' fuel-economy value of new vehicles sold in September was 24.6 miles per gallon, down 0.3 mpg since August." Still, the publication says that the average fuel economy of new vehicles sold in September is still up 0.8 mpg compared with September 2012.

The decrease in fuel economy of new vehicles sold indicates that automakers have been moving larger vehicles like full-size pickup trucks and large SUVs in greater volume. For example, Ram truck sales are up 8 percent compared with September 2012, and so far in 2013, are up 23 percent compared with a year ago. Ford F-Series pickups are also selling well, seeing an increase of 9.8 percent compared with September 2012, and up 20.7 percent year-to-date compared with the same time period in 2012.

On the other hand, sales of vehicles with better fuel economy are on the decline. For example, Toyota Prius sales (including Prius, Prius c, Prius V and Prius Plug-in) are down nearly 42 percent in September compared with August, and are down 16.1 percent compared with last September. If you’re shopping for a hybrid, now is a great time to get a good deal.

Gas prices may not fall too much lower at this point. Reuters reports that the price of crude oil fell in September, which allowed refineries to lower prices. In the last couple weeks though, crude prices have fallen very little, so Reuters reports that it is unlikely that gas prices will get much cheaper than they already are.

In the market for a new car? Check out the U.S. News rankings of this year's best trucks, cars and SUVs. Then, look for a great deal on a new vehicle by checking out this month’s best car deals. Also, be sure to follow us on Twitter and Facebook.