In four minutes, you can improve your car’s fuel economy by 4%.
http://www.bbc.com/autos/story/20160527-how-to-save-a-billion-gallons-of-petrol
Back in 2008, during one of the more memorable exchanges in the US Presidential race between then-Senator Barack Obama and Senator John McCain centred on offshore drilling — its value to the American nation, or lack thereof. Sen Obama took an unusual approach to the argument: He focused on tyre pressure. “Making sure your tyres are properly inflated, simple thing, but we could save all the oil that they’re talking about getting off drilling, if everybody was just inflating their tyres and getting regular tune-ups,” he said. “You could actually save just as much.”
Replied Sen McCain: “My opponent doesn’t want to drill, he doesn’t want nuclear power, he wants you to inflate your tyres.”
Obama’s claim — that simply maintaining proper tyre pressure could save as much fuel as the country stood to gain from offshore drilling — sent fact-checkers scurrying for answers. Could it be true? Could such a simple trick — managing four tyres’ PSI can be accomplished in about four minutes — really improve fuel economy by 4% and, collectively speaking, save a billion gallons of petrol a year? The answer, according to the US Government Accountability Office, is an emphatic yes. Notes a GAO memorandum dated 9 Feb 2007: “The Department of Energy’s designated economist on this issue indicated that, of the 130 billion gallons of fuel that the Transportation Research Board (TRB) estimated were used in passenger cars and light trucks in 2005, about 1.2 billion gallons were wasted as a result of driving on underinflated tires.”
The memo notes that in 1999, underinflated tyres contributed to the deaths of nearly 250 motorists and caused the injuries of some 25,000 more.