Gas saving tips from the savingfreak

With gas prices skyrocketing out of control it seemed like a good time to review all the ways we can save on gasoline.

Cheap Price Sites -There are three sites I use to check for gas prices: Gasbuddy.com, GasPriceWatch.com, and MSN Autos.  No one of these gets all the stations but you can be sure to get the best prices by using a combination of them.

Inflate your tires -You hear this all the time but the numbers are staggering.  You can reduce gas mileage by as much as 15% driving on underinflated tires (it also shortens the life of your tires).
Use the right oil -You can increase your fuel economy 1-2% by using the manufacturer's recommended grade.  Also look for oil that says energy conserving on the label.  That means it has extra additives to reduce friction.
Get out of the city -Big cities will many times have their own gas taxes and thus just crossing the city line can drop the price drastically.
Use the cheap stuff - Studies have shown that unless your car is specifically made for the higher octane fuels that they really do not help our hurt your car or gas mileage.
STP Gas Treatment - This stuff is actually proven to work and can help clean out your fuel system in about three treatments (some people see immediate results).  Plus treating your car with Jet Fuel is  just cool.  I saw this on Amazon for $1.79 for 8 oz, but buy it locally because the shipping is off the chart.
Tighten the gas cap - Gasoline will evaporate if given a means of escape so make sure the gas cap is tight and that it is not broken and letting out the gas vapor
Don't top off -If you fill your tank too much the excess gas can seep out when it is sloshing around.  So when you get close to being full just turn of the pump and be sure to jiggle the handle and get the excess out of the hose.
Hit the shade -The hotter your car gets the more chance for evaporation out of the gas tank.  Also running your air conditioning can reduce gas mileage.
Keep it in tune -A car that is out of tune or fails an emissions test can reduce your gas mileage by as much as 4%.  If you have a misfiring spark plug it can take you down as much as 30%
Replace your air filters - If your air filter gets clogged up and won't let the air pass easily it can reduce your fuel economy by as much as 10%.  The recommendation for changing them is every 3,000 miles.