By Jennica Peterson

Here’s an excuse to order french fries: Leftover fryer grease from restaurants can be converted into ecofriendly biodiesel fuel. And if you’re traveling to Hawaii, you can rent a car powered by recycled vegetable oil. Bio-Beetle on Maui and Oahu offers Volkswagen Beetles and Golfs and Jeep Liberty SUVs starting at $199 a week. The nifty vehicles have all the power of a regular car, and they get 20 to 45 miles to the gallon. After you fill the tank, you’re good for some 500 miles. The islands each have one fueling station, located near the airports. Biodiesel costs about the same as regular gas or a little less. So go ahead and supersize those fries.

Tradewinds U-Drive, Oahu, (888) 388-7368; Maui Car Rentals, (800) 567-4659; www.bio-beetle.com.