We talk most often about electrics or hybrids, but when it comes to fuel efficiency, the best technology available today to go far with the minimum amount of energy remains the diesel engine. Nothing beats it, and nothing even comes close. Take the car above, a Volkswagen Passat TDI BlueMotion. It’s a family car with a 1.6-liter 105-hp diesel engine. It’s not a fast car, it’s a very efficient sedan optimized for fuel economy, and only provides adequate performance, about like a Honda Civic hybrid, but with more torque at low rpm.

Gavin Conway, a British journalist from The Sunday Times, took a Passat BlueMotion for a ride, and driving very conservatively, he managed to go 1531 miles on one single tank. Driving on a mix of roads, highways and cities, the average speed was a slow 45-mph, with fuel economy an exceptional 64.2-mpg. Would a Prius have got better mileage? This question remains open, but the Volkswagen Passat has the advantage of a larger tank, giving much better range…

So Gavin Conway has set a new Guinness World Record for the distance traveled by a production passenger car on a single tank of fuel. Who will beat it?