NEW YORK (TheStreet) -- Even with deliciously low gas prices, having to visit the pump more often than not can be a bitter pill to swallow. And, besides, the most fuel-efficient cars can save you thousands

So, if you're in the market for a new car, truck or SUV, you should look out for makes and models that get terrible gas mileage -- and despite new federal regulations, years of high gas prices and a dawning environmental awareness among many Americans, they're still out there.

The 2015 fuel economy guide from the U.S. Environmental Agency and the U.S. Department of Energy rates the gas mileage of most vehicles in the U.S. We highlighted which ones in each class do the worst.

Below are the cars and trucks with the worst fuel efficiency for 14 vehicle categories from two-seater cars to minivans. There are ties in several categories, such as subcompact cars and large cars, meaning that there are 25 vehicles to avoid.

Check out the list to see which brands were the worst of the lot. And when you're done with that, check out TheStreet's best-of-breed list of the most fuel efficient vehicles for 2015.

Infiniti QX50

In the small station wagon category: Infiniti's 2015 QX50 has a 3.7 liter, 6-cylinder engine and gets an average 20 miles to the gallon. It has a manufacturer's suggested retail price between $35,000-$37,200.

Kia Sedona SXL

Two vehicles sported the worst gas mileage for the minivan category. First, the Kia Sedona SXL (shown above): Its 3.3 liter, 6-cylinder engine and gets an average 19 miles to the gallon. The Kia minivan has a manufacturer's suggested retail price of $39,700.

Toyota Sienna AWD

As well, the Toyota (TM) Sienna AWD: Its 3.5 liter, 6-cylinder engine and gets an average 19 miles to the gallon. The Toyota minivan has a manufacturer's suggested retail price of $33,860-$46,150.

Mercedes-Benz E63 AMG S 4matic (Wagon)

In the midsize station wagon category, the Mercedes-Benz E63 AMG S 4matic (Wagon) has the worst gas mileage. The vehicle has a 5.5 liter, 8-cylinder turbo engine and gets an average 18 miles to the gallon. The Mercedes wagon has a manufacturer's suggested retail price of $103,200.

Nissan Xterra 4WD

For small sport utility vehicles, the Nissan (TYO) Xterra 4WD has the worst gas mileage. The vehicle has a 4.0 liter, 6-cylinder engine and gets an average 17 miles to the gallon. The 2015 Xterra has a manufacturer's suggested retail price between $25,710-$31,640.

Nissan Frontier 4WD

For small pickup trucks, the Nissan Frontier 4WD has the worst gas mileage. The vehicle has a 4.0 liter, 6-cylinder engine and gets an average 17 miles to the gallon. The 2015 Frontier has a manufacturer's suggested retail price between $25,400-$35,260. 

Aston Martin DB9

For mini-compact cars, the Aston Martin DB9 has a 5.9 liter, 12-cylinder engine and gets an average 15 miles to the gallon. The Aston Martin has a manufacturer's suggested retail price starting at $187,000.

Maserati GranTurismo Convertible

For subcompact cars, the Maserati GranTurismo Convertible (shown above) has a 4.7 liter, 8-cylinder engine and gets an average 15 miles to the gallon. The GranTurismo Convertible has a manufacturer's suggested retail price between $145,740-$182,009.

Mercedes-Benz C63 AMG Coupe

Also in subcompact car category, the Mercedes-Benz C63 AMG Coupe has a 6.2 liter, 8-cylinder engine and gets an average 15 miles to the gallon. The C63 AMG Coupe has a manufacturer's suggested retail price of $62,950.

Bentley Continental GT Convertible

The Bentley Continental GT Convertible, the final subcompact car, has a 6.0 liter, 12-cylinder engine and gets an average 15 miles to the gallon. The vehicle has a manufacturer's suggested retail price between $206,300-$250,100.

BMW 760Li

Four cars in the large car category tied for the worst gas mileage. First, the BMW 760Li (shown above) has a 6.0 liter, 12-cylinder turbo engine and gets an average 15 miles to the gallon. It has a manufacturer's suggested retail price of $141,200.

Mercedes-Benz S600

The second car, the Mercedes-Benz S600, has a 6.0 liter, 12-cylinder turbo engine and gets an average 15 miles to the gallon. It has a manufacturer's suggested retail price of $166,900.

Mercedes-Benz S65 AMG

As well, the Mercedes-Benz S65 AMG, has a 6.0 liter, 12-cylinder turbo engine and gets an average 15 miles to the gallon. It has a manufacturer's suggested retail price of $222,000.

Rolls-Royce Ghost

The Rolls-Royce Ghost, the final car in the large car category, has a 6.6 liter, 12-cylinder turbo engine and gets an average 15 miles to the gallon. It has a manufacturer's suggested retail price of $291,000.

Toyota Tundra 2WD/4WD

For standard pickup trucks, the Toyota Tundra (both the two-wheel-drive and four-wheel-drive version) has a 5.7 liter, 8-cylinder engine and gets an average 15 miles to the gallon. The Tundra (shown above) has a manufacturer's suggested retail price between $28,410-$44,825.

Ram 1500 4WD

As well, the Ram 1500 4WD has a 5.7 liter, 8-cylinder engine and gets an average 15 miles to the gallon. The Ram 1500 has a manufacturer's suggested retail price between $28,920-$52,875.

Chevrolet Camaro

For the worst gas mileage in compact cars, General Motors' (GM) Chevrolet Camaro (shown above) has a 6.2 liter, 8-cylinder Supercharger engine and gets an average 14 miles to the gallon. The Camaro has a manufacturer's suggested retail price between $23,705-$72,305.

Rolls-Royce Phantom Coupe

As well in compact cars, the Rolls-Royce Phantom Coupe has a 6.7 liter, 12-cylinder engine and gets an average 14 miles to the gallon. The Phantom Coupe has a manufacturer's suggested retail price starting at $433,550 for the 2014 model.

Mercedes-Benz G550

In standard sport utility vehicles, the Mercedes-Benz G550 (shown above) has a 5.5 liter, 8-cylinder engine and gets an average 13 miles to the gallon. The G550 has a manufacturer's suggested retail price of $115,400.

Mercedes-Benz G63 AMG

Its sister SUV, the Mercedes-Benz G63 AMG also has a 5.5 liter, 8-cylinder engine and gets an average 13 miles to the gallon. The G63 has a manufacturer's suggested retail price between $119,450-$137,100.

Bentley Mulsanne

In the midsize car category, the Bentley Mulsanne has a 6.8 liter, 8-cylinder turbo engine and gets an average 13 miles to the gallon. The Mulsanne has a manufacturer's suggested retail price of $303,700.

Ferrari FF

As well, the Ferrari FF (shown above), owned by Fiat Chrysler (FCAU) , has a 6.3 liter, 12-cylinder engine and gets an average 13 miles to the gallon. The 2015 Ferrari FF has a manufacturer's suggested retail price of $349,900.

Chevrolet Express 3500 2WD Passenger

In the passenger van category, the Chevrolet Express 3500 2WD has a 6.0 liter, 8-cylinder engine and gets an average 12 miles to the gallon. The Express 3500 has a manufacturer's suggested retail price between $34,485-$49,640.

GMC Savana 3500 2WD (Passenger)

Also in the passenger van category, the GMC Savana 3500 2WD (shown above) has a 6.0 liter, 8-cylinder engine and gets an average 12 miles to the gallon. The Savana 3500 has a base price of $33,200.

Bugatti Veyron

The worst gas guzzler for 2015 is one only those in the upper echelon will be able to afford. The Bugatti Veyron, in the two-seater car category, has an 8.0 liter, 16-cylinder engine and gets an average 10 miles to the gallon. It has a manufacturer's suggested retail price between $1.49 million-$1.69 million.

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