I went an extra 10 lbs to see if I could squeeze out better mpg. It helped a little but the wife came home and said something seems wrong with the car,she said it rides rough and clunky. we just went on a 150 mi trip over some poor roads and I noticed everything in the glove boxs was ratteling and the car felt like I was driving down the railroad tracks. lots of vibrations and a harsh feeling in the stering wheel. It was not a good idea.....joe -PS.Its been cold here in MN. the shocks and strut oil could be stiff too