Running in ?

[slowrunner]

I know modern cars don't need running in, but having just read the post about MPG I'm a little confused. I've had a MY16 4HS for 4 days now. My first journey unfortunately was a 200 mile 'round trip. I filled up, reset the MPG value on the MMCS and watched it more than the road on the way there and back. When I arrived back home it was 38.2 MPG - not bad I thought for an almost pure petrol drive.

Yesterday I did a 38 mile round trip with a full charge and was EV all the way there and at least 5 miles on the way home. Gentle/slow driving the whole way. This time once the MPG started to display it briefly showed something like 800mpg then quickly went to mid 40s.

This did not concern me when I thought this was the 'petrol only' value, but reading the previous post, if this including the EV part in the miles then the figure is terrible !

OK - so its only the second journey I've made, and like most scientific endeavor 'we need more data', but am i missing something. Does the car get better over the first few runs/days/months ?

I'll know more once I've filled it up with fuel for the second time and can measure tank to tank against odometer.

 

[westdevon]

I know modern cars don't need running in, but having just read the post about MPG I'm a little confused. I've had a MY16 4HS for 4 days now. My first journey unfortunately was a 200 mile 'round trip. I filled up, reset the MPG value on the MMCS and watched it more than the road on the way there and back. When I arrived back home it was 38.2 MPG - not bad I thought for an almost pure petrol drive.

Yesterday I did a 38 mile round trip with a full charge and was EV all the way there and at least 5 miles on the way home. Gentle/slow driving the whole way. This time once the MPG started to display it briefly showed something like 800mpg then quickly went to mid 40s.

This did not concern me when I thought this was the 'petrol only' value, but reading the previous post, if this including the EV part in the miles then the figure is terrible !

OK - so its only the second journey I've made, and like most scientific endeavor 'we need more data', but am i missing something. Does the car get better over the first few runs/days/months ?

I'll know more once I've filled it up with fuel for the second time and can measure tank to tank against odometer.[/figure

The mpg figure is for the whole trip and you'd expect to get 60 to 70 mpg over 38 miles.

It sounds to me like you were looking at the manual figure that shows mpg since last reset. Combine the two trips and that might work out at something in the forties.

 

[anko]

Yesterday I did a 38 mile round trip with a full charge and was EV all the way there and at least 5 miles on the way home. Gentle/slow driving the whole way. This time once the MPG started to display it briefly showed something like 800mpg then quickly went to mid 40s.

From the above isolated statement, one would indeed conclude that your "petrol part" of the trip was done at approx. 20 MPG. Did you perhaps engage Charge mode when he engine started and forgot to turn it off? As that is the only way I could explain these numbers.

 

[maby]

38 miles is probably about the worst distance for measuring fuel consumption - you've done your 20 to 30 miles on EV giving an effective infinity mpg, then the petrol engine kicks in cold with a flat battery. Any petrol engine starting from cold delivers pretty poor fuel consumption for the first few miles and the PHEV will burn some extra petrol to bring the battery level back up a bit.

Don't pay too much attention to fuel consumption calculated over short periods - it can be very misleading on the PHEV. The instantaneous fuel consumption swings around from such extremes - effectively infinite mpg in EV mode to zero mpg when it is sitting still, recharging the battery. Look at the figure over a period of weeks or months to work out how well it is performing for you. Different owners also get widely differing figures depending on their pattern of usage. If you can run primarily on EV, you can see the hundreds of miles per gallon that some report, but if like me your usage includes a lot of long journeys, then your average will come out at something like 45mpg.

 

[greendwarf]

Perhaps, as this is a MY16, the MMCS software has been tweeked to show current MPG rather than overall, so that previous observations about what this means are no longer correct :? In which case what the OP saw seems right.

I wonder if the dashboard figure matched the MMCS one? This is less likely to have changed in the facelift.

 

[anko]

My trip to my primary work location is approx. 25 miles. Sometimes just inside EV range but, as temperatures are dropping, most of the time just outside EV range. At the end of my trip, I see fuel consumptions reported of 0.1 l / 100 km (2800 MPG) - 0.5 l / 100 km (560 MPG), depending on circumstances. My secondary work location is a bit further away: 60 miles. For these trips I see values between 3.5 l / 100 km (80 MPG) and 4.5 l / 100 km (62 MPG). These values totally make sense and I see no reason no to trust them.

If I saw 40 MPG on a 38 mile trip, I would want to know why.

 

[anko]

Perhaps, as this is a MY16, the MMCS software has been tweeked to show current MPG rather than overall, so that previous observations about what this means are no longer correct :? In which case what the OP saw seems right.

If that were the case, 11 l /100 km (or 25 MPG) would have been more likely. And it would not explain why he briefly saw 800 MPG.

 

[gwatpe]

The OP did state that the mpg fig started at 800mpg. This surely means that it was an "auto reset" data and not the "man" data.

My PHEV still returns the same sort of numbers after 45000km to when new. Have a much more informed understanding of the systems with logging of car data over the last few months.

having a recorded cents/km operation cost shows the interactions of the gas pedal, and terrain and brake, with usage of the ICE and Battery. Unless the Electricity is free, we still need to be easy on the accelerator to keep the operation costs low.

If the software has been changed this seems like more rubbery figs from MMC. At least the 2014-15 models readings could be used if the trip meters were reset as well.

 

[jaapv]

You cannot measure consumption over such short distances. The influence of traffic conditions, variations in driving style, wind, etc. are far too great. Only longer periods and longer distances can give the correct figures.

 

[anko]

You cannot measure consumption over such short distances. The influence of traffic conditions, variations in driving style, wind, etc. are far too great. Only longer periods and longer distances can give the correct figures.

The fact that there are factors influencing fuel economy does not mean you cannot measure it. Also the existence of such factors do not impact the correctness of such measurements. Not even on short trips. You only have to be a bit careful with interpreting the numbers you see.

And yet, I believe it is save to say that the numbers seen by the TS are way outside the normal range: If you get 40 MPG on a 38 mile trip, of which 24 were GRID miles and 14 were hybrid miles, it translates to 40 / 38 * 14 = 14.8 MPG over the hybrid section of your trip. I wonder what kind of circumstances you have in mind, that would result in a 14.8 MPG over a distance of 14 miles ....

As TS claims 24 miles EV range, his driving style cannot be that bad :mrgreen:

 

[maby]

In the case of the PHEV, I think it simply a question of how the displayed fuel consumption figure is calculated. When I've been running fuel consumption tests recently, I've seen some pretty silly figures displayed transiently at the transition between pure EV and serial hybrid with a flat battery. You are transitioning from a period of infinite MPG to an eventual steady state of about 40mpg if you continue to drive for a long distance on a flat battery. As you enter serial hybrid with a cold engine and flat battery, you can go through several periods of really pretty terrible fuel consumption as the engine warms up and brings the battery level back up on the upwards side of the hysteresis cycle. If you are stationary in traffic during those periods, it translates to very poor mpg figures - in the middle of winter I've seen our PHEV transiently report 8mpg.

The OP's figures do seem to be extreme, but I notice that he describes it as a "round trip" but does not specify its duration. The Auto Reset mpg figure clears down to zero after four hours, doesn't it? If he spent more than four hours at the mid point, then the balance of the measured trip will be very different - he reports that the first five miles of his return journey were done in EV and the rest on petrol - under those circumstances it is quite possible that the display would transiently show 800mpg after the battery went flat, but soon settle at the standard 40ish mpg that it the default performance of the car.

 

[anko]

The OP's figures do seem to be extreme, but I notice that he describes it as a "round trip" but does not specify its duration. The Auto Reset mpg figure clears down to zero after four hours, doesn't it? If he spent more than four hours at the mid point, then the balance of the measured trip will be very different - he reports that the first five miles of his return journey were done in EV and the rest on petrol - under those circumstances it is quite possible that the display would transiently show 800mpg after the battery went flat, but soon settle at the standard 40ish mpg that it the default performance of the car.

Good thinking. That might be it.

40 MPG / 19 * 14 is approx. 30-ish MPG (9.4 l / 100 km) which would still be stiff, but not unthinkable.

 

[jaapv]

You cannot measure consumption over such short distances. The influence of traffic conditions, variations in driving style, wind, etc. are far too great. Only longer periods and longer distances can give the correct figures.

The fact that there are factors influencing fuel economy does not mean you cannot measure it. Also the existence of such factors do not impact the correctness of such measurements. Not even on short trips. You only have to be a bit careful with interpreting the numbers you see.

And yet, I believe it is save to say that the numbers seen by the TS are way outside the normal range: If you get 40 MPG on a 38 mile trip, of which 24 were GRID miles and 14 were hybrid miles, it translates to 40 / 38 * 14 = 14.8 MPG over the hybrid section of your trip. I wonder what kind of circumstances you have in mind, that would result in a 14.8 MPG over a distance of 14 miles ....

As TS claims 24 miles EV range, his driving style cannot be that bad :mrgreen:

Very true -that is the moment to start questioning the measurement.

 

[anko]

Very true -that is the moment to start questioning the measurement.

Assuming you have read there last two posts as well, you will agree with us that is more likely an issue with interpretation of the results than with the measurements as such?

 

[jaapv]

Quite possible, but by no means certain, I would not dismiss one or the other. Feel free to substitute methodology, if so desired.

 

[slowrunner]

Very good point about the 'round trip being split up - yes I'm sure it was more than 4 hours before the return journey. So for just the return half of the journey I'm pretty happy with that. Having looked in the manual (always a last resort :lol: ) I now know about the 'auto-reset'

Is a way to turn the auto-reset off ?

 

[anko]

Is a way to turn the auto-reset off ?

Well, that is what the Manual mode is for. There are two readings: M(annual) which only resets when you want it to and A(uto) which resets after every 4 hour brake.

 

[slowrunner]

I think I've got it now - manual and auto are separate numbers - pressing the button chooses which one is displayed, but both are maintained all the time. At first I thought it was a single number and the button changed when the number was reset.

Thanks for you help - I'm loving the PHEV more each drive, especially now I've had a chance to do a few 'all electric' trips. Just the front camera to sort out - separate thread methinks...

 

[HHL]

I think I've got it now - manual and auto are separate numbers - pressing the button chooses which one is displayed, but both are maintained all the time. At first I thought it was a single number and the button changed when the number was reset.

Yes, quite confusing. I thought too when pressing manual it would just not reset automatically, but they are actually two separate display modes and it always goes back to auto when the car is restarted.