Many drivers are proud of their ability to squeeze a few extra miles per gallon out of their cars. Hypermilers take things a little more seriously, coasting into every stoplight and driving well below posted speed limits in the pursuit of maximizing fuel economy. Helen and John Taylor of Melbourne, Australia have gone even further, and turned hypermiling into their life's work.

This summer the Taylors are in the United States, aiming to drive through all 48 contiguous states on a 9,600-mile journey. The pair will traverse the country in an unmodified 2011 Chevy Cruze Eco with a manual transmission.

During one stretch of the trip, the Taylors will attempt to travel 2,000 miles on a single tank of gas, achieving nearly 160 mpg over a segment that one might imagine will include a lot of downhill driving. Under normal conditions the couple estimate that they will be able to achieve a 23 percent increase in fuel economy simply by employing standard green driving techniques, like those they teach at their Melbourne-based Fuel Academy. The school organizes events and holds workshops around the world coaching drivers on how to cut their fuel consumption.

Over the entirety of the trip, the Taylors will attempt to break their own U.S. record of 67 mpg, set in 2009 in a Volkswagen Jetta TDI. The pair have tended to rely on clean diesels like the Jetta TDI in their record-setting attempts through the years, because of their superior efficiency on the highway.

In 2008, the Taylors set the world record for diesel fuel economy when they circled the coast of Australia in a diesel-powered Peugeot 308 HDi 110 in 25 days, posting the American equivalent to 75.6 mpg on the trip. In 2006, they drove around the world in 78 days, traveling 18,470 miles and averaging more than 52 mpg.

The couple currently hold 88 hypermiling records and have taken on sponsorship from Shell Oil to help fund their record setting attempts and hypermiling clinics. On Shell's Smarter Driving website, fans can check in on the Taylors to monitor their progress. Currently, the couple are in the second week of their trip, passing through the northeast United States.