(CNN) In 2015, two men drove a car through all 48 contiguous U.S. states on less than $300 of diesel fuel, or just eight tankfuls.

During the 8,233 mile trip they achieved a fuel economy of 81.17 miles per gallon, or 2.89 liters per 100 km.

They trounced the official rating for the car they used -- a VW Golf TDI rated by the EPA for 31 and 45 mpg in city and highway driving respectively -- earning a world record

How did they do it? By applying a technique know as 'hypermiling,' which anyone can use to slash their fuel consumption, no matter which car they drive.

'Tutelage and inspiration'

The two drivers, Wayne Gerdes and Bob Winger, weren't new to this: they had, in fact, beaten their own previous record of 77.9 mpg obtained on the same route in 2013.

The very term 'hypermiling' was coined by Gerdes in 2004, and it became the Oxford Word of the year in 2008

Wayne Gerdes with his stock Honda Accord, which he gets as much as 60 mpg out of.

"I defined it is simply as beating the EPA in whatever you own and drive," he says.

Gerdes hold several other records. He once pushed a Honda Insight hybrid to four times its rating, achieving 220 miles per gallon on a 15-mile drive.

In 2008 he drove a stock Toyota Prius on an all-highway, 805-mile route from New York to Chicago on a single tank of fuel (he arrived with a gallon to spare).

Similarly, last year, he drove a RAM 1500 truck from Los Angeles to Denver on a single tank , while climbing over the Rocky Mountains in mid-winter.

But when asked which of his achievements he is most proud of, he says: "Actually those of others hypermilers behind the wheel, thanks to my tutelage or simply inspiration."

How to save fuel

Hypermiling can be achieved fairly easily with just a few tactical adjustments to one's driving behavior.

Graphic: CNN/Aaron Darveniza

Most techniques, such as the ones shown above, are mainly common sense, but when compounded into a habit they can provide tangible results.

"I normally spend about 1/3 to 2/3 the amount that the average driver does on fuel," says Gerdes.

The savings can be significant, especially in regions where the cost of fuel is higher than in the U.S..

For example, in the U.K., where a gallon of gasoline currently costs around $5.60, hypermiling could save the average driver doing 8,000 miles in a 33 mpg car around $500 a year, according to Gerdes.

Hypermiling is generally characterized by a smooth driving and thinking ahead. Aggressive tactics like tailgating, which entails closely following the vehicle ahead to reduce drag, are against Gerdes' philosophy: "I always drive at or just below the Posted Speed Limit in the far right lane."

"A simple drive down any highway will show you the aggressive and far less efficient drivers bouncing from one person's trunk to the next.

"You can spot the individual beating their car's EPA rating leaving gaps of upwards of 7 to 10 seconds from the vehicle ahead in the far right lane, trying to maintain momentum."

Other widely accepted hypermiling tips include shifting up as soon as possible (generally at 2,500 rpm or below), an immaculate maintenance of the vehicle, and even driving shoeless to achieve maximum finesse over acceleration and braking.

'Drive less'

Gerdes believes saving fuel could make the U.S. less reliant on oil imports, with deep-reaching consequences to its foreign policy: "If we cut our consumption by about one-third, we wouldn't need to import a drop," he says.

Fossil fuel combustion is also the main driver of global warming: "Every gallon saved means avoiding about 29 pounds of CO2 emissions."

But could hypermiling survive once self-driving cars take over?

"I'm a huge fan of autonomous cars: they will allow everyone to become a hypermiler.

"The new mantra will not be 0 to 60 or the top speed a car can achieve, it will be how safe and comfortable the ride will be.

"If you want to read a newspaper on your commute to work, you'll want a smooth ride, and that will allow for more widespread fuel savings."

Until then, he says, "Drive less when you can. And much smarter when you do."