3.683 MPG Error tonight; Who ya gonna believe?

The trick, obviously, is to fill it to exactly the same level twice in a row, and then calculate miles vs gallons.

This is harder to do than on some other cars because the seal between tank and nozzle may fool the pump into shutting off too soon.

but they strongly recommend against over-filling. It's better to remain in ignorance of your exact mileage than to over-fill the tank.

Or you can calculate your mileage based on many tankfulls, thus reducing the amount of the error that differing levels introduce.

It has been reported by users that the mpg given on the display is somewhat different than the mpg you get by calculating gallons and miles.

 

Similar problem this morning.

I've been beeping since Monday.

I've been getting about 44 MPG, so I went a full 40 miles past the beep.

It started at 250 and I went to 290. The screen mileage said 43.3 MPG when I filled.

(It was dry, 63 degrees and sunny, the car was warmed up.)

I put in .... 6.146 gallons.

I had the fill on the normal middle position and after the first shut off, I let it sit and then gently pressed the handle to see if anymore would go in, and it shut off immediately. That was all I was going to get in there safely and cleanly.

So, let's figure this out. If I went 290 miles and used 6.146 gallons, that means that I'm getting 47.2 MPG. But the screen says 43.3 ... that's a 9% difference.

What's more, I put in 6.6 gallons last time ... I filled within 10 miles of the beep and I put in more gas (and got the same mileage ~43 for the tank on the screen, I didn't compute it based on the fill).

I'm not complaining about the car in any other way. I just feel like the environmental benefit of the car is diminished if I have to fill up twice as often. Though the evaporative emissions on refuelling are not that great, especially a state with these super nozzles, it's still a large part of the VOC pollution I'm contributing to with this car and if I could cut that in half, I would.

The only fun part about this morning is after the screen reset and I drove to work and parked ... I had 96 MPG, sure it's only 1 mile from the gas station, but it still feels nice to see that.

 

Over time if you keep an overall average, you will get accurate numbers, but from tank to tank it can vary widely.

It is funny how they recommend against "topping off" the tank. When you can put another 1.5 - 2 gallons in the tank after it shuts off the first time, your not really 'topping off', your filling the stupid tank.