NEW YORK (TheStreet) -- Springtime is around the corner and that means it's time to put your shades on, put the top down and just drive. 

With gas prices low, it's more affordable than ever -- but cars that get bad gas mileage are still going to cost you more at the pump. And convertibles, many with big engines and sporty performance, can be among the worst offenders. 

"Some vehicles probably manage aerodynamics better than others with the top down," according to an email from a fueleconomy.gov spokesman. Fueleconomy.gov is a joint resource from the U.S. Environmental Agency and the U.S. Department of Energy for consumers seeking more information about fuel economy when purchasing a vehicle.

Meaning, if you drive a sporty convertible all-year-round, even if it gets bad gas mileage, you'll probably do better in the winter. 

However, "the difference is highly vehicle-dependent and probably makes negligible difference at lower speeds of typical city/urban driving," the spokesman wrote. "Assuming there is greater aerodynamic drag with the top down, and thus a negative impact on fuel efficiency, it would become more noticeable at higher speeds as a result of the relationship between the power required to overcome drag with vehicle speed."

What other way to drive a convertible with the top down on a nice spring day is there than at "higher speeds"?

We've culled the latest fuel economy guide by fueleconomy.gov, for convertible sports cars with terrible gas mileage. Note: the combined mileage data is not adjusted for driving with the cars' tops down, according to fueleconomy.gov, citing the EPA.

Check out these 20 convertible sports cars with notoriously bad gas mileage. And when you're done with that, check out TheStreet's best-of-breed list of the most fuel efficient vehicles for 2015.

20. BMW M4 Convertible

The 2015 BMW M4 Convertible has a 3.0 liter, 6-cylinder Turbo engine and gets a combined city and highway mileage of 19 miles to the gallon. It has a manufacturer's suggested retail price of $72,500.

19. Mercedes-Benz SL63 AMG

The 2015 Mercedes-Benz SL63 AMG has a 5.5 liter, 8-cylinder Turbo engine and gets a combined city and highway mileage of 19 miles to the gallon. It has a manufacturer's suggested retail price of $147,300.

18. BMW 650i xDrive Convertible

The 2015 BMW 650i xDrive Convertible has a 4.4 liter, 8-cylinder Turbo engine and gets a combined city and highway mileage of 19 miles to the gallon. It has a manufacturer's suggested retail price of $97,900.

17. Infiniti Q60 Convertible

The 2015 Infiniti Q60 Convertible has a 3.7 liter, 6-cylinder Turbo engine and gets a combined city and highway mileage of 19 miles to the gallon. It has a manufacturer's suggested retail price of $48,550.

16. Jaguar F-Type V8 S Convertible

The 2015 Jaguar F-Type V8 S Convertible has a 5.0 liter, 8-cylinder Supercharger engine and gets a combined city and highway mileage of 18 miles to the gallon. It has a manufacturer's suggested retail price of $92,000.

15. Audi RS 5 Cabriolet

The 2015 Audi RS 5 Cabriolet has a 4.2 liter, 8-cylinder engine and gets a combined city and highway mileage of 18 miles to the gallon. It has a manufacturer's suggested retail price of $79,200.

14. McLaren Automotive 650S Spider

The 2015 McLaren Automotive 650S Spider has a 3.8 liter, 8-cylinder Turbo engine and gets a combined city and highway mileage of 18 miles to the gallon. It has a base price of $283,925.

13. Ford Mustang Convertible

The 2015 Ford (F) - Get Report Mustang Convertible has a 5.0 liter, 8-cylinder engine and gets a combined city and highway mileage of 18 miles to the gallon. It has a manufacturer's suggested retail price between $23,800 and $41,800.

12. Jaguar XK Convertible

The 2015 Jaguar XK Convertible has a 5.0 liter, 8-cylinder Supercharger engine and gets a combined city and highway mileage of 17 miles to the gallon. It has a manufacturer's suggested retail price of $90,500.

11. Mercedes-Benz SL65 AMG

The 2015 Mercedes-Benz SL65 AMG has a 6.0 liter, 12-cylinder Turbo engine and gets a combined city and highway mileage of 17 miles to the gallon. It has a manufacturer's suggested retail price of $214,500.

10. BMW M6 Convertible

The 2015 BMW M6 Convertible has a 4.4 liter, 8-cylinder Turbo engine and gets a combined city and highway mileage of 16 miles to the gallon. It has a manufacturer's suggested retail price of $118,200.

9. Aston Martin Vanquish

The 2015 Aston Martin Vanquish has a 6.0 liter, 12-cylinder engine and gets a combined city and highway mileage of 16 miles to the gallon. It has a manufacturer's suggested retail price of $296,295.

8. Bentley Continental GT Convertible

The 2015 Bentley Continental GT Convertible has a 6.0 liter, 12-cylinder Turbo engine and gets a combined city and highway mileage of 15 miles to the gallon. It has a suggested retail price between $206,300 and $250,100.

7. Aston Martin V8 Vantage

The 2015 Aston Martin V8 Vantage has a 4.7 liter, 8-cylinder engine and gets a combined city and highway mileage of 15 miles to the gallon. It has a suggested retail price between $98,200 and $153,195.

6. Maserati GranTurismo Convertible

The 2015 Maserati GranTurismo Convertible has a 4.7 liter, 8-cylinder engine and gets a combined city and highway mileage of 15 miles to the gallon. It has a suggested retail price between $145,740 and $182,009.

5. Aston Martin DB9

The 2015 Aston Martin DB9 has a 5.9 liter, 12-cylinder engine and gets a combined city and highway mileage of 15 miles to the gallon. It has a suggested retail price between $188,295 and $213,295.

4. Mercedes-Benz SLS AMG GT Roadster

The 2015 Mercedes-Benz SLS AMG GT Roadster has a 6.2 liter, 8-cylinder engine and gets a combined city and highway mileage of 15 miles to the gallon. It has a suggested retail price of $228,080.

3. Audi R8 Spyder

The 2015 Audi R8 Spyder has a 4.2 liter, 8-cylinder engine and gets a combined city and highway mileage of 14 miles to the gallon. It has a suggested retail price between $129,400 and $199,600.

2. Ferrari 458 Speciale Spider

The 2015 Ferrari 458 Speciale Spider has a 4.5 liter, 8-cylinder engine and gets a combined city and highway mileage of 14 miles to the gallon. It has a suggested retail price of $263,553.

1. Lamborghini Aventador Roaster

The 2015 Lamborghini Aventador Roaster has a 6.5 liter, 12-cylinder engine and gets a combined city and highway mileage of 12 miles to the gallon. It has a suggested retail price between $441,600 and $548,800.