1,100 Miles, 28 Hours, 14 Countries, 1 Tank of Fuel

Audi AG has set a Guinness World Record with its A6 TDI Ultra midsize sedan for traveling through 14 countries on a single tank of fuel. A pair of drivers covered 1,158.9 miles during the nearly 28-hour trek in an unmodified A6, averaging more than 60 miles per gallon.

The record-setting A6 Ultra is powered by Audi's standard 2.0-liter four-cylinder diesel engine and has a 19.3-gallon fuel tank. Air pressure in the car's low-rolling-resistance tires was managed during driver changes to optimize efficiency.

British motoring club RAC Ltd. (formerly Royal Automobile Club) helped coordinate the event and plotted the driving route to avoid heavy traffic areas and mountains. During the trip, however, the A6 had to detour around an accident and a closed tunnel that briefly put it on less fuel-friendly mountain roads. The last 16 miles of the trip were driven with the car's trip computer indicating the fuel tank was empty.

Automotive journalist Andrew Frankel and Porsche race car driver Rebecca Jackson took turns behind the wheel. After starting in the Netherlands, they passed through Belgium, Luxembourg, France, Switzerland, Lichtenstein, Austria, Germany, Italy, Slovenia, Croatia, Bosnia and Serbia before finishing in Hungary.

The car was driven at an average speed of about 50 mph during the trip. It achieved 76 mpg on the European driving cycle, which is 13% more efficient than its official 67 mpg rating.