Can anyone fill me in on nitrogen filled tires on a 2009 Impala? Does this require taking the car for service? Is it expensive? Thanks!

They put nitrogen in the tires to help with gas mileage from what I understand. Not sure on the cost of it though

Tires with regular air will reduce pressure as the temperature goes down - about a pound for every 10*F. Tires with nitrogen do not soften as much. Some tire places will inflate with nitrogen as part of the price. I personally would not pay to have nitrogen. I check my tire pressures monthly and keep close track of my fuel usage.

they use nitrogen because it doesn't expand and contract with the temperature changes in order to get the full benefit of this though you have to take them in to a shop that does nitrogen because if you mix air and nitrogen it negates the benefits of nitrogen.