PHILADELPHIA (Reuters) - As U.S. gasoline prices hit records on almost a daily basis, an increasing number of motorists are following a radical driving technique designed to eke out every last mile from a tank of fuel.

Known as 'hypermiling,' the method can double gas mileage, even in gas-guzzling vehicles that would normally get less than 20 mpg.

Promoted on a growing number of Web sites, hypermiling includes pumping up tires to the maximum rating on their sidewalls, which may be higher than levels recommended in car manuals; using engine oil of a low viscosity, and the controversial practice of drafting behind other vehicles on the highway to reduce aerodynamic drag -- a practice begun a few years ago by truck drivers.

The price of gasoline -- which hit a record of nearly $3.61 per gallon on Tuesday, according to travel club AAA -- has rapidly emerged as the public's biggest economic concern............;_ylt=AjKbvTEnGdVAaOMdzRkJJsMuQE4F