I may not have read every post, but I did not see any mention of the first thing that came to my mind. If I were trying to optimize mileage on a heavy SUV that travels mostly on the highway and is not used for Towing, I would make sure it had a cam that is optimized for low RPM and then I would put in a differential that put the RPMs at about 2000 at 65 mph in high gear. Of course, the parts would have to come from the junk yard or I would never break even.
There are plenty of 2007 Suburbans for sale in my area for under $10,000.
The 1999 Suburban has a highway rating of 17 MPG, the 2007 is 20 MPG highway. To buy a newer truck is more practical than spending a couple of thousand trying to improve the fuel economy of the old 5.7L.
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I used the EPA mileage figures in the way they are meant to be used, as a comparison between two vehicles and not as a measure of what anyone will actually get. The EPA/DoE tells us that the figures are for comparison between vehicles someone might want to buy. They do bear some resemblance to what people get, but not everyone drives the exact way the government test is set up. I just got a new car and my gas mileage is right at the EPA highway number because I drive mostly highway on my 32 mile commute to work
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My 2008 Toyota Yaris has a EPA sticker rating of 29 city and 36 highway. I almost never get less than 40 mpg out of it though.
At 175,000 miles, Iām still on my original factory brake pads, a coincidence? I think not! Drive like the brakes donāt work and you get amazing gas mileage.
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