As gasoline prices have increase over the last several years, many people have resorted to very creative ways to increase gas mileage. These drivers – commonly referred to as “hypermilers” – try to push their car to get the best fuel economy possible, and many have been able to double their car’s EPA estimated gas mileage.

While most of their tips revolve around driving the correct speed and making sure your car is in top shape, many of their “extreme tips” are dangerous and should not be attempted under any circumstance. Here are some of the more egregious trips that you should never consider using no matter how badly you’d like to increase your car’s fuel economy:

Cruising through stop signs. Rolling through stop signs will help you save gas because you won’t need to use as much energy (read: fuel) to get back up to whatever speed you’re supposed to be traveling. In the end, this probably won’t save you too much gas, and could end up costing you a lot of money.

Blowing through stop signs is a bad idea for a couple reasons. First and foremost, it’s against the law, and if you get caught you can expect to get a nice fine and probably a hike in your insurance premiums – which will, without a doubt, more than negate any money you save on gas. Second, it’s dangerous. By running stop signs you’re increasing the chance of hitting a pedestrian and getting into an accident.

Recommendation: No matter how desperate you are to increase your fuel economy, I think it’s safe to say that running through stop signs isn’t something you should be doing.

Tailgating large trucks (think 18 wheelers). Here’s another dangerous idea that should always be avoided. When you’re tailgating or “drafting” behind a large vehicle, you’ll increase your car’s fuel economy because you won’t have to overcome as much air resistance; in turn, you’ll use less fuel.

When traveling closely behind an 18 wheeler, you are putting yourself in the driver’s blind spot, meaning he or she can’t see you and probably don’t even know you’re behind them. Obviously, part of being a safe driver is knowing where all the other vehicles around you are so that you can plan and act accordingly.

Also, the closer you drive to any vehicle, the less reaction time you have if something were to go wrong. If you’re only a couple of feet away from a big rig’s bumper you’re not going to be able to avoid an accident should the truck need to attempt to come to an abrupt stop.

Recommendation: Travel a safe distance behind all vehicles (remember the three second rule?) and travel the speed limit, especially on the highway.

Shutting off your car while it’s still moving. This tip will help increase fuel economy because, as expected, if your car’s engine is off, it’s not using any gas. This tip is often used while a car is traveling down hill, so that it can use not only the energy generated while the car was on, but energy generated from gravity as well.

It should be fairly obvious that this is an absolutely terrible idea. If your car is off and you’re still in motion, the chances of something bad happening are increased exponentially. You won’t have the ability to quickly accelerate to get out of a tight spot; you’ll lose power steering, making it more difficult to turn the vehicle; and chances are if you turn the steering wheel too far, you’ll end up locking it in place.

While it’s tough to pick the worst extreme hypermiling tip, this one should certainly be in consideration.

Recommendation: When going down hills simply let off the accelerator and let gravity do its job.

Over inflating your tires. By over inflating your tire pressure by 20 or so pounds per square inch (PSI), you apparently will see a slight increase in fuel economy because you’ll have less tire surface on the road – meaning you’ll need slightly less energy to get the car moving and maintain speed.

However, with this decrease in tire contact with the road comes a decrease in traction and an increase in the chance you will be unable to maintain control of your vehicle. Also, over inflating tires will make them more susceptible to blowouts and uneven wear.

Recommendation: Simply make sure your tires are inflated to the car manufacturer’s recommended PSI. This should be more than enough to help get better fuel economy.

While it’s nice to increase your vehicle’s fuel economy, it’s not worth risking your life.

Stick to the tried, true and safe methods you’ve heard ad nauseum over the last year or so: drive the speed limit, make sure your tires are properly inflated, use moderate acceleration, etc. You likely won’t double your gas mileage this way, but you will save money at the pump while being a safe and courteous driver.