2023 Prime: Anyone Figured Out Tank Average MPG?

What exactly are you wanting here ?
If you EVER plug it in......there is no such thing.

 

Well it seems that Toyota chose not to spend the money to develop and provide you that kind of a number.

In addition to cost, it might actually not be a reasonable thing to do IF the vehicle is propelled at times by BOTH energy sources
at the same time.......which I strongly suspect that it is.

With my Ford Hybrid, it is easy to see that happening......a LOT.
With the Prius C, it is a bit more difficult to tell when that is happening......or if it is at all.

 

It's not necessarily about giving "everything you can", it's more about using the power sources in the most efficient way. I've turned on the power distribution display on my Prius HEV occasionally, and the battery is often used at highway speeds even on cruise control(flat terrain). I expect the computer keeps the engine at a constant load and uses the battery to account for any minor changes in demand from wind or slight changes in terrain.

 

Not really. If you want MPG while the ICE on only, then you will get a dismal number. For my 21 PP it was around 43mpg IIRC. This is the engine only MPG, so no Hybrid mode EV miles. You can get this number if you drive above 72mph with no substantial down hill.

What you want to know is HV mode only MPG with no EV mode from the wall charge. The car does not display this. Only way to estimate it is to drive a tank full without charging.

BTW, Ford does the same thing. The MPG displayed is simply (total miles driven) decided by (the amount of gas used). No distinctions for HV and EV portion of the drive.

 

Does it really still clamp at 99.9? Toyota should know that's just daft, given a WLTP combined fuel consumption of 0.7 l/100km, or over 300mpg(US).

You'd have to be doing very little charging to get as bad as 99.9mpg, or 2.35 l/100km. 99.9 is absolutely what I'd expect the average display to be if clamped there.

European models avoid this by approaching 0.0 l/100km, rather than infinite mpg.

And Japanese models would mostly avoid it by using km/l - 99.9km/l is 235 US mpg, so less likely to always hit a 99.9 clamp, although you still would.

Insufficient attention paid to countries with the biggest 'consumption' numbers.

 

Oh, 99.9mpg clamp? That's strange. I think he is seeing 999.9mpg. The first year Gen4 PP (2017MY) had a 199.9mpg limit on the display. It was quickly updated for the following MY with 999.9 MPG limit. This is the number I got if I'm doing only EV mode drive. As soon as the engine started, it went down precipitously.

 

Wow! So, Toyota went backwards on the Gen5 display. So strange.

Posted via the PriusChat mobile app.

 

But is the engine off because of normal hybrid operation, or because electricity from the grid is being used? Miles traveled by the car in hybrid mode with the engine off are miles still driven by the energy in gasoline.

 

Yes, but it did not come from the grid if you did not charge the traction battery. If you only measure the miles driven while ICE is ON, then your mpg will be much lower than a regular hybrid Prius would report. As I said, the only way you can get a semi-accurate tank average MPG without counting grid power is to drive it like a regular hybrid Prius without charging the traction battery from the wall.

 

Since the Gen5 tank average now has an upper limit of 99.9 mpg as you showed us, it will not show you anything higher if you drive most of the distance on EV mode. The only way you will see a meaningful number would be when you are driving most of the tank without charging. If you are on a long trip and do only have an initial traction battery charge, it will be lower than 99.9mpg.

Doesn't Gen5 show the average mpg for the trip meter and for the life-time mpg on ODO like it did on Gen4?

 

Set the car to show average MPG, drain the battery to zero range, reset the MPG by holding "enter," and Bob's your uncle. It should then show you your non-electric MPG. Or if you don't trust the MPG on the dash, drain battery to zero, fill up and reset trip odometer, drive a full tank, then do the math old school.

Have I missed something here?

You want to drain it to zero EV range first though, not just switch into HV manually, as it will very slowly draw down the battery in HV mode if there's EV range left.

 

In this case, as you said you filled half a tank at the end, I'm wondering if your refuel at the start of the test was small enough that it failed to reset the tank average measurement, so you're getting a lot of EV driving from before the fill-up included in your "tank average".

 

You weren't driving in hybrid mode with the grid charge portion of the battery fully depleted. You were driving in HV mode with that portion partially charged. Since your car was depleting that portion while in HV mode, it is simply impossible to calculate the HV mode average mpg.

And where did the energy in the hybrid battery come from? Without a plug, that energy would have originated from the gasoline in the tank. A PHEV placed in HV mode should be maintaining the battery SOC at the same point, so the energy for all the HV electric miles would also come from the gasoline.

Here we have some grid charge being used up in HV. The amount used can be estimated. That energy amount can be added to the energy amount of the gasoline used to calculate a mpge figure. The car wasn't just using grid energy from the battery though. It was also adding charge back with gasoline energy. Since the EV miles in the display was just the times the engine was off, we have no way of knowing how much of that energy for those miles came from the grid or gasoline. Those miles could easily be from coasting downhill, with no energy being expended.

If you want to know the fuel efficiency of the car in hybrid mode, drive it in EV mode until it switches over, and then start tracking. Preferably for three tanks. Doing otherwise opens the measuring up to more variables and errors.