As the average price of a gallon of regular gas varies between $3.50 and $4 nationwide, fuel efficiency remains prized among the new cars most people buy. But some drivers are too rich to care about gas costs, or need or choose to drive cars or trucks that are big and heavy. As a result, the least fuel-efficient cars fall into two categories — ultra high-end luxury cars and large vans and SUVs.

Read: The Biggest Gas Guzzlers on the Road

Cars with high gas mileage like the Toyota Camry, Corolla and Prius and the Honda Civic, Accord and CR-V remain at the top of the best-selling cars in America list every month. With small four-cylinder engines, most of these vehicles get an average of 30 miles per gallon (mpg) or better.

At the other end of the spectrum are some sports cars that get 14 mpg or less. These sports cars have one other thing in common. They have price tags of over $100,000, and in some cases $2 million. Each has eight-cylinder engines, or more, and often those engines are turbo-charged to create more horsepower. They are toys for the rich, and what their owners pay for gas is a tiny fraction of what they paid for the vehicle itself.

The second category of gas guzzlers are big trucks used for hauling people or freight. With a weight of nearly three tons — and that is before they are loaded — their engines need to be large.

Based on data provided by the U.S. Department of Energy on fuel efficiency for all cars and light trucks, 24/7 Wall St. identified the least fuel-efficient vehicles in America. Average mpg is based on a combination of city and highway driving. For each of the 10 least fuel-efficient cars, we considered fuel efficiency, engine type and the cost of fuel over the course of a year, as well as the cost of the vehicle. Car research firm Edmunds provided registration numbers for the past five years from R.L. Polk. Edmunds or the vehicle manufacturers themselves also provided car prices. The annual cost of fuel is based on 45% highway, 55% city driving, 15,000 annual miles and current fuel prices. Those fuel prices are, of course, rising daily.

These are the least fuel-efficient cars in America.