Whitemarsh Supervisor McLenigan is Doing Her Part...

(Jean also owns and rides this Harley/Davidson motorcycle that gets upwards of 45-48 mpg...ed.)

Whitemarsh Supervisor Jean McLenigan's car is far more fuel efficient than you might expect. The silver sedan, a '97 Mercedes E-300 diesel, can make it up to 200 miles on a gallon of ... cooking grease.

McLenigan is one of an estimated 10,000 Americans driving a diesel vehicle converted to run on waste vegetable oil, according to Justin Carven, president of Greasecar Vegetable Fuel Systems.

Carven says his company has sold 4,200 conversion kits in the past seven years, including one to McLenigan, and the demand is continuing to rise with the price of gasoline.

Read more about Jean's lack of dependence on foreign oil.