256 Miles Range?

[MylesG23]

I get about 20mpg City, I filled up my 2001 STS and it said 256 Miles range...shouldn't it be around 400?

[submariner409]

Range constantly adjusts with long term average mileage calculation: You fill up after a stretch of city, low gas mileage driving, the estimated range is down. You fill up after a 400 mile highway trip, the estimate says you'll make well over 400 on this tank.

One trick is to never reset the long-term mileage. That way, it cycles up and down ever more slowly as the mileage changes average out over many miles and gallons. If you want to get some ides of what's happening right now, or about how your driving habits affect mileage, switch to instant averaging for a while, but don't reset the long term.

Say you drove 65 mph for 30 minutes and got 28 mpg. Then you got stopped in traffic for 30 minutes. Your average for that hour is 14 mpg, and it takes a lot of mileage to bring that 14 back to 20 or 25.

[Ranger]

Another way of putting it is that your range is based on the current AVG MPG.

[N*Caddy]

Also if you recently disconnected the battery terminals (resetting everything) then the algorithm estimating your range will start with bad average (thus a small range).