Hybrid MPG

[DWM1980]

Hi All

I’ve recently changed my D4 V90 for a T6 Recharge. For obvious reasons I haven’t had much of a chance to drive it yet, but initial impressions are good.

I have a question about the displayed MPG. I drove around 24 miles during a journey on Friday. The TA MPG in the car displayed 62.5. The value via the app was 80.4 MPG (0.2 gallons used). It also recorded an electrical consumption of 7.4 kWh and regeneration of 2.4 kWh. Can anyone explain what’s going on here and why the value recorded by the car is so different? Is it some sort of average or equivalent MPG, taking into account the electrical use etc?

Cheers

Dave

[dling]

When cold outside, the heater uses petrol to warm up the cabin. The TA accounts for the consumption of that petrol. The VOC does not. You can notice this better on rides that are fully electric: the VOC shows 0 gallons used while the TA will show the amount used by the heater.

[DWM1980]

Many thanks for your reply and sorry for not responding sooner.

I have a follow up question I'm afraid, and I aplogise if its a bit stupid. How do I work out an 'equivalent' MPG, bearing in mind that the app gives one MPG value, the car gives another, and then on top of that, there is the electrical consumption to consider?

The reason for wanting to know, in addition to just being interested in these things, is that if I use the car for business trips, I simply claim back the fuel costs (its a company car so other costs are taken care of). I therefore need a way of working this out.

Based on the values given by the VOC app, I guess it would be easy to work out a cost per mile based on the fuel and electrical energy used, however this wouldn't take into account fuel used for heating etc (or is this so insignificant, it doesn't really make much difference?).

Am I overthinking this, or is it as complicated as I am making it?

Cheers

Dave

[sk546]

To do a proper calculation to work out fuel costs, yes, it is that complicated to work out unfortunately. Something to make it even more complicated is if you do an electric only journey without kicking in the ICE, the MPG recorded neither increases or decreases so there is no benefit detailed on either the VOC app or within the car.

Fuel usage for heating etc varies quite a bit from very insignificant to quite substantial depending on a number of factors like journey type & length, outside air temp, amount of ICE running time and cabin temp settings. If you are worried about it though, you can turn off the additional heater within SENSUS so no fuel is used but both the cabin and the engine block will remain cold until the ICE switches on.

For business trips, the most beneficial and easiest way to calculate costs is to charge per mile completed at the standard business rate of 45p/mile. This negates the need to start trying to convert all the recorded figures into an 'equivalent' MPG.

[Director76]

I do a monthly download of journeys from the on call app, calculate an average mpg based on total petrol only used and miles done and then use HMRC fuel rates to calculate the pence per mile. Sounds complicated but it’s not.

If I do lots of business journeys they are longer trips and the monthly mpg falls so the ppm figure goes up, sometimes way above the published allowable company car rate.i use this rate each month to calculate my expense claim and because it represents a robust, auditable car specific rate I believe that there is no taxable benefit.

For a company car, you can’t claim £0.45 without incurring a benefit and no T8 can match the <2000 cc standard published ppm rate without its driver subsidising the business miles.

I don’t factor electricity into that, I donate a free full charge towards each company journey, but as home pottering is almost all electric I do benefit from the hybrid more than the company in the round!!

[Philip Fisher]

Originally Posted by sk546

........Something to make it even more complicated is if you do an electric only journey without kicking in the ICE, the MPG recorded neither increases or decreases so there is no benefit detailed on either the VOC app or within the car..

I don't believe this is correct. When I run around using only electric, the MPG displayed in the car increases. If was recently reset it increases more quickly than if it was reset a longer time ago (as would be expected for an average figure).

[sk546]

Originally Posted by Philip Fisher

I don't believe this is correct. When I run around using only electric, the MPG displayed in the car increases. If was recently reset it increases more quickly than if it was reset a longer time ago (as would be expected for an average figure).

I'm glad it works as you would expect it to in your car but in my case it doesn't happen that way so believe what you want.
I thought it was odd when I first took delivery of the car but have since got used to it.

[Director76]

I think the journey mpg in the driver performance app on sensus does take account of electric only, 'zero fuel' miles, as you chart very high mpg figure on pure drives (assuming some fuel heater usage), with the journey mpg then falling rapidly when the battery is depleted or running on hold, eventually, on long trips stabilising (around 28-29mpg!)

The 'TA' mpg on the driver display, i'm not sure. I don't think I reset it on the last T8 for about 25k miles and it settled almost immovably on 39.6mpg. Now if this wasn't assuming a 0 mpg figure (or fuel heater only usage) for electric running I'd be pretty certain that the fuel only consumption average would be a lot less than 39.6mpg, mysterious!

[Philip Fisher]

Originally Posted by sk546

I'm glad it works as you would expect it to in your car but in my case it doesn't happen that way so believe what you want.
I thought it was odd when I first took delivery of the car but have since got used to it.

I am not believing what I want. I am simply saying that your experience does not match mine. I was politely suggesting that perhaps you were mistaken. However If you are absolutely sure that is how it works on your car then there are only 2 possibilities:-

1. They changed the way it works in later models
2. There is a fault on your car (or indeed mine).

So what does everyone else's car do?

[Philip Fisher]

Reading Director76's comment above it would appear his MY21 matches the way my MY16 works. So perhaps it is a fault on your car?