I run my 08 XB with 40 lbs. of air in tires for fuel efficiency during the non winter months. I recently was offered nitrogen from a tire store as a test customer . Nitrogen is claimed to be better for fuel efficiency. I get a little more MPG that i estimate to be less then one MPG but get a great improvement in the ride. I recommend the nitrogen for ride improvement. Seems the tire weighs less with nitrogen and the ride at highway speeds is greatly improved. I am a senior citizen and not a gadget person. I believe this is worth consideration. Steve

http://blogs.consumerreports.org/cars/2007/10/tires-nitrogen-.html

http://ask.cars.com/2007/10/nitrogen-tires.html

http://www.bargaineering.com/articles/nitrogen-filled-tires-better-gas-mileage.html

I'm not sold on it. I think if it were free i would do it but if I have to pay its not worth it.

My mom got it in her jeep for free. Can't remember if she said she noticed a difference. I will have to ask her again.

Pressure is pressure. Pound for pound it does exactly the same thing. Any improvement in ride quality is in the head of the driver. The same goes for fuel economy gains. Nitrogen's "big" advantage is that it does not increase in pressure as it heats up nearly as much as air (which is mostly nitrogen anyway). Racing cars have used nitrogen for years for its PSI stability. Sorry, but it is no magic bullet.