WATERBURY, Conn. (AP) – Police and automotive experts say over-the-top attempts by some drivers to boost their gas mileage could be endangering them and other motorists.

The AAA and Connecticut State Police are warning against extreme measures in “hypermiling,” a practice in which unusual techniques are used to boost vehicles’ mileage.

They include rolling through stop signs, turning off a car’s engine to coast down hills, overinflating tires to decrease rolling resistance against pavement and other techniques.

One action that authorities say is particularly dangerous is called “drafting,” tailgating big rigs in hopes of cutting wind resistance and being pulled along in a truck’s wake.

“Every one of them is illegal,” Connecticut State Police spokesman Trooper William Tate said of the “hypermiling” techniques.

“But more importantly, they’re extremely dangerous. Every one of them is the cause of accidents,” he said.

Most accidents on secondary roads are caused by drivers who don’t obey traffic signals, such as stop signs or traffic lights, Tate said. Most highway crashes are caused by tailgating and unsafe lane changes, which are often related, he said.

“Following a tractor-trailer too closely, you don’t have the ability to see beyond it as you would when following a passenger vehicle,” Tate said. “You’re risking your life, and the lives of motorists behind you.”

Fran Mayko, a spokeswoman for AAA Connecticut Motor Club, says “hypermiling” has been around for a while, but that it has drawn more attention as gas prices have jumped and drivers are seeking ways to boost their mileage.

This is the first time AAA has issued a warning about it, she said.

“These folks who are extremists, apparently they get 70, 80, 90 miles a gallon,” she said.

She said drivers should stick to tried-and-true mileage boosters: keeping up with routine maintenance, ensuring tires are properly inflated, keeping unnecessary weight out of the car and driving at the posted speed limit.

According to the U.S. Department of Energy, gas mileage typically decreases rapidly at speeds above 60 mph. Every 5 mph that a driver goes above 60 mph is like paying an additional 30 cents per gallon of gas, according to the government.

AAA said the average Saturday for regular unleaded gas nationwide was $4.07 per gallon, up $1.10 from the same time last year.

Connecticut’s average was about $4.37 per gallon for regular unleaded, an increase of $1.17 over last year.

The most expensive region in Connecticut on Saturday was in greater Bridgeport, where the average for regular unleaded gas was $4.47 per gallon. The New London and Norwich area had the cheapest gas, averaging $4.32 per gallon, according to the AAA.