Is My Lifetime MPG Actually Higher Due to 199.9 EV MPG?

Your ODO corresponding mileage includes EV miles at 199.9 MPG just like your Trip meter corresponding mileage. Unfortunately there is no easy way to calculate real HV (gas) only mileage on PRIME. Your real HV (gas) only mpg is less than 65MPG, unless you have done absolutely no EV mode drive on your car.

One thing I should mention is that ODO corresponding mileage is not always for the "life time". It is only for "since last reset". The value can be reset anytime by long pressing TIRP button or from the 11.6" screen "Past Record" section. I have not tried it, but I think removing 12V battery may also reset the value. I knew about the TRIP button reset, but did not know about the info section on the large screen. Updating the past record on the screen reset my MPG on ODO inadvertently.

 

Summary: There is no "infinity" involved and no magic.
The MPG figure is: miles driven divided by gas used.
Easy. Simple.
And yes that automatically factors in distance traveled using the battery only.

 

One way to get "real" HV (gas) only mileage is to drive PRIME strictly on HV mode after a fresh fill-up and use the "full tank" method to hand calculate mpg after next fill-up. I have done this several times on my PRIME, but I found out much easier way to estimate your recent full tank mpg is to look at the DTE right after you fill up your tank. The DTE miles are strictly based on HV mode drive and amount of gas in your tank. Right after a fill-up, the DTE number is roughly equal to last tank's mpg x 9.3 gal.

Therefore, if you have 500 miles on the DTE after fresh fill-up your last tank mpg was 500/9.3= ~53.8mpg

See this thread for more information.
What is your DTE after fill-up? | PriusChat

 

No correlation between ev and mpg

 

Wierd, mine is a combination of EV mileage and gas mileage.

 

The 199.9 mpg display when in EV is a stupid and totally unnecessary limit that Toyota put on the 2017 Primes. Hopefully, the person who made that decision was properly flogged. Later, they somehow realized that the leftmost digit can display a "9" just as easily as a "1." But that's not your real question.

When on odometer, the average mpg is simply the number of miles driven since the last rest divided by the number of gallons since the last reset. (That's the same methodology as on trip A or B.) Mine was pegged at 199.9 mpg from the day I bought it used and reset the stats till the day I started out on a 6,000 mile road trip. The real number the day I got that first tank of gas was about 392 mpg after driving my first 2280 miles and buying 5.8 gallons before I hit the road on the big trip.

 

No difference in 2017 and 2020 PRIME. All PRIME models show combined miles/gas used.

 

Really? The converted number is going to be HV (gas) only mpg??? How so?

 

No, that's not what he meant. It just shows you your mpg in metric format. However, it's not very precise since it's usually around 0.5 or 0.6L/100km. The difference between those two is pretty big in mpg. Still, it's better than that stupid constant 199.9.

 

Meh, start a spreadsheet. Toyota's numbers are definitely rose-tinted I'm not sure why, suspect they're just addicted to hyperbole. And your numbers will survive a battery disconnect.

 

It's not 199.9 mpg (mine actually shows 999.9, not 199.9 mpg). It's ∞ mpg. However, the display can't show higher than 999.9; so, you're seeing 999.9 or 199.9, instead of ∞.

Whatever mpg figure you're seeing is miles driven per gasoline used. If part of it is EV driving, that contributes as ∞ mpg or 0 gpm (gallons per mile), which artificially results in a higher mpg figure than the actual gasoline mileage. EV driving is not factored in as a finite number into the mpg figure.

 

If you're only using Chargepoint, you can roughly estimate the actual HV gas mileage. Look at the total kWh used, and subtract the EV miles from the odometer by allocating about 25 miles for each 6 kWh. This is your actual HV miles. You can then multiply the odometer mpg by the HV miles and divide by the odometer miles to get the HV mpg.

My odometer is currently at about 4,200 miles and 74 mpg, and my Chargepoint is showing 96 kWh. Therefore, my HV mileage is about 67 mpg. I'm trying to improve on that and bring it to 70 mpg (HV only). This is better than the EPA and Consumer Reports estimates, which seem to be geared toward heavy-footed drivers.

 

What ?? Why ??
Is there some good reason that you thing that would be more accurate ?
Hint: it won't be.

 

It won't. But some of us are a little OCD and like to compare. Problem is that the L/100km is such a gross approximation when you're converting back & forth between three digit whole numbers and single digit fractions. 0.4 L/100km is 588 mpg. 0.5 L/100km is 470 mpg. That's quite a difference. Mine will range from 0.5 to 0.6 (392 mpg). It would help if the metric went to 2 decimal places, but it would help a lot more if the English just showed the freakin' number like it does on the newer models.

 

Oh, I see, @Tideland Prius means L/100km display is useful to check the mpg beyond 199.9 limitation on 2017 PRIME models. Well, I don't have to worry about that anymore. I got 2020 model now showing up to 999.9 mpg. I will never need to know value higher than that.

 

A broader answer to this question is it depends. There is no regulation so manufacturers can include ev miles, regen, etc. or not.

 

Rub it in. ...