Originally Posted by kam327
But why are you expecting a 3mpg gain from the shutters if the EPA rating is only 2 mpg higher, and that's with the use of lower rolling resistance tires and aero wheel covers? So if the combination of the shutters and wheels/tires gives you a 2mpg gain, I don't think you can expect more than 1mpg from the shutters alone.
If my car would get anywhere NEAR the EPA rating with the shutters I'd be interested. It seems no matter what, the BEST I've ever gotten, ALL highway, was 34mpg. NEVER have I gotten a tank to average more than that, even though my EPA rating is supposed to be 38 hwy. So... if my car was EPA tested WITH the shutters and I end up at 34 on AVERAGE instead of the 29-30 I get now, I'd be pleased.
Besides, how do you know it's only going to net 1mpg? Have you done the conversion yourself? I would like to think that the design behind them is capable of more than 1mpg gains over not having them, otherwise there wouldn't be much of a reason to invest in their development and implementation.