I just started to use the Range setting to see how many miles I have until I am empty. I put gas in my car today and the Range said 406 miles. I drove 30 miles home from work, and the range got down to 295. Anybody else experiencing this?

 

I think the system continuously calculates the range based on your driving style, speed, miles driven, etc. This is my theory.

 

"Miles to Empty" is an estimate and can never be anything else. It extrapolates an estimated range based on the miles per gallon figures you've averaged so far. Consider how your average mpg for highway driving is likely considerably higher than your average mpg for city driving. If you're out on the highway, your "Miles to Empty" will therefore increase compared to city driving—but it will decrease again shortly after you exit the highway. Likewise, the worst mpg you get is when you're stopped with the car running (whether in traffic, at a red light, sitting on line for the drive-up ATM, etc., doesn't matter what the reason is), so if you idle your car for long periods that will negatively affect your "Miles to Empty" as well. But there's no way for the car to know that you're going to get stuck in a traffic jam, or that you plan to get on the highway for 400 miles, or whatever—it can only estimate based on the driving you've done. (Heck, sometimes I don't know which road I will take next if I happen to be driving at rush hour!)

 

Going down the Grapevine (a very long steep hill) the miles to empty will start counting backwards after a couple minutes of coasting with my foot off the gas.

 

I don't bother looking at the range calculation until I'm around a 1/4 tank- by that time the MID has pretty much converged on my MPG and there only 5-7 gallons left so any calculated .vs. actual MPG error is limited because there are fewer gallons left.

The range is a second button push of the MID that I rarely use. I usually fill up at 1/4 tank and there is still 6-7 gallons left as a reserve so there is plenty of range even at 19mpg like I usually get.