The Ford Crown Victoria is many things; cheap, reliable, and the preferred transportation method for many of America’s police forces. One thing it is not is fuel efficient, unless you swap the big V8 for, say, a Cummins 4BT turbodiesel. How does 40 MPG in a big American sedan sound to you?

This video is over two years old, and the project itself is more than 5 years old. But you don’t need a whole lot of details other than to know that the 4BT Cummins engine came out of a bread van, with a transmission “borrowed” from a Ram 2500 pickup. All that was stuffed into a heavy-duty Crown Victoria Police Interceptor, which can be picked up for a song and a dance at municipal auctions. If there’s one thing Cummins knows, it’s diesel engines, and while the 4BT diesel engine is about 200 pounds heavier than the V8 engine it replaces (and makes less power too), this rugged motor has just as much torque and fuel economy Crown Vic owners dream about.

The builder claims he can get 33 MPG in mixed driving, and topping out at nearly 40 MPG while cruising on the highway. At best, most Crown Vic owners see 25 MPG while moseying along at the speed limit, but 40 MPG? That’s the kinda thing most people only dream about. It also sounds a helluva lot cooler than the 4.6 liter mod motor it replaces, and even more modern police interceptors can’t break the 30 MPG mark. Imagine how much money cash-strapped municipalities would save? Then again, it’d be pretty easy to outrun the nose-heavy diesel Vic, which has just 105 horsepower for pursuit purposes.

Perhaps most importantly though, this is an uncomplicated and cheap project that turns a gas-guzzling car into a fuel sipper, and one that’d make a helluva daily driver too. Add a bigger turbo and other mods, and you could really get some power outta this engine too. Perhaps diesel-powered Crown Vic should be the first Gas2 project car?