LEWISTON, Maine — The Maine guys who created a vehicle propelled by Coke Zero and Mentos candies are in the Big Apple.

Fritz Grobe and Stephen Voltz are in New York to demonstrate their contraption Tuesday on the “The Late Show with David Letterman.” They’ll do an encore on “The Early Show” on CBS.

Their Coke-and-Mentos-powered machine gets its momentum from a piston mechanism that utilizes the bubbling mixture created when the candy is dropped into 108 two-liter bottles of Coke Zero. The Sun Journal newspaper says they promised the NYPD that they wouldn’t exceed the speed limit.

The Buckfield-based entertainers shot to fame four years ago with their online videos demonstrating geysers created by Diet Coke and Mentos.