Specifically, i have a 2011 Hyundai Elantra, but would be interested in other cars as well.

One of the functions on the dash after “MPG” is “Range”. Now, the MPG is a cumulative average since the last refill. But does anybody know how the “Range” is calculated?

I just filled up and, pulling away from the station, getting 8 mpg, the range said 380. Once up to speed, and now with 30 or so mpg cumulative on this tank, the range said 379. So clearly it’s not really based on the current cumulative mpg, or it would have shown something like 100 at first, then 380 later.

I can think of basically three ways to do this calculation, to varying degrees of accuracy and usefulness:

- When the tank is filled, the range just resets to 380 as a typical range, and counts down based solely on the odometer. Not very accurate, but easy.
- Calculate based on the average mpg for that tank, and the amount of gas left in the tank.
- Calculate based on the average mpg since the engine was started, or that trip, day, etc. and the amount of gas left.

Obviously, since its already calculating mpg, it has some method to measure or at least approximate fuel flow, and so calculating how much fuel remains is just a matter of fuel flow and time.

2 and 3 are the better solutions, but neither of these seem to be what my car is doing.

Does anybody know how it is typically calculated, for most cars, or for a 2011 Elantra specifically?

Thanks!