The mileage on my replacement Blazer is a bit low.
15 MPG, where the last Blazer ran about 18 MPG.
A friend reccomended Berryman's B-12 gas additive. Says it's $2.97 at Walmart. Found it at Walmart. top shelf, and this store had only two left, so it took a while to find it. A couple days ago, I put in one can of that B-12 fluid. I'd checked my mileage at 15.2 on the last tank. This next fill up came up 16.3 MPG. I don't think I changed my driving style, and the weather is much the same. So, I'm figure that fluid did some good.
It may work for you, also.