[DifferentPointofView]

Hey, "The Jeep Guy" here, I just wanted to say that, I don't seem to see any difference between 55 and 60mph, I actually see a better miles per tank when I drive 60 rather than 55. My ZJ has a 23 gallon fuel tank, so I'm guessing that it's pretty accurate at fill-up because more gallons are used than smaller vehicles. I've taken my factory roof racks to try and improve the mpg, but I don't feel or see a difference at fill up. But one thing I do notice while driving is it's much easier to accelerate on a half full tank than a completely full one. I've also noticed that I've gotten a slight but noticeable increase in fuel economy after replacing my OEM Air filter to a K&N Filter.

I'm Also thinking back to the whole truck thing where a truck actually gets better highway mpg with the tailgate up than down because of the dome effect created within the tailgate. Theoretically this would create drag, but in a wind tunnel it in fact creates the opposite.

With a large displacement engine, there's also usually a large car. I think that if your going at 60mph, the weight of the vehicle causes the momentum to continue on longer and, since momentum has built up at this higher speed it's easier on the engine cause the weight is pulling the car forward and helping out the engine. I've been in V8 Cadillac's with Instant fuel economy, and when I watch it, it seems that when as the car accelerates to a faster speed, the fuel economy goes up when they put on the gas. I'm guessing that from the large displacement, lets say 4.7L, at idle speed of like 15 mph there is still alot of extra fuel being injected into the engine and fuel is wasted, but with a little bit on the gas you go faster and there isn't much more fuel being injected cause it doesn't take much more RPM to get it from 0-60. I never have to go over 2000 RPM to go anywhere, and My Jeep shifts at 1500 if I accelerate lightly. I can easily get from 0 to sixty hitting the gas barely at all. If I wait long enough The Jeep can Idle at 20mph.

This could be why that Intrepid had a flat mpg curve at speeds over 60, it was a heavier car, and once you get a heavy car going, it goes, and the car doesn't have to do much more to go from 60 or from 70mph. I love coasting in my Jeep, cause it coasts for miles and my rpm's are near idle.

Also, with the SuperMid, Where do I buy one and can I get it in US Customary?