Calculating economy

[alexanderfoti]

Hello all

I have been commuting in the plug in hybrid c class for 3 weeks now.

As I can do the entire commute on electricity only, it's fuel efficiency calculations have been quite straight forward.

After start shows 999mpg and an average of 3m/pkwh usually. If I drive somwhere longer than the battery range, I reset the after start when I run out of battery power, and it then represents an accurate mpg for that trip (as its only showing me efficiency readings on the energy from the diesel)

Tank averages is where it gets complicated.

I reset the after reset when I bought the car and filled the tank. Up until recently all the driving has been electric. However a 350mile journey has meant that this "after reset" figure now includes 310 miles of diesel running and 40 odd miles of electricity only (from the wall).

Now, the car does seperate out miles with engine running and miles with engine off, as below:


However, on the after reset figure, this obviously includes a big chunk of wall charging which throws the numbers off. Additionally, driving in hybrid mode with an "empty" battery, inlucdes a significant amount of engine off running as per the screenshot.


Yes I am boring
No I have nothing better to do on my weekend break.

Thoughts appreciated!

 

[alexanderfoti]

Here is after reset for example:



My best solution so far, is to remove the eV off mileage that I know (from the commute which is repeatable) from the after reset and then use this as a basis for the calculations.

This has its issues, as sometimes I may use both for overtaking etc, so won't be that accurate.

 

[Uncle Benz]

And in other news, having a life is an option

 

[alexanderfoti]

No life
Only work

I will come up with a solution.

 

[Uncle Benz]

No life
Only work

I will come up with a solution.

Hurry up. All work and no play, etc

 

[alexanderfoti]

Potential solution

EVSE counts KWh
Add the KWh Per charge as a fill up on my mile tracker app. (fuelio)
Add the diesel fill ups as usual, minus the milage from the eV fill ups when doing so.

Its getting too complicated

 

[V6Matty]

I’m sure there’s an app for this

 

[alexanderfoti]

There is (fuelio) but it treats EV's as 2 tank vehicles.

if there was no hyrbid stuff it would be easy.

Deduct EV miles from total tank miles and that gives you EV usage and Diesel usage.



The best way I have figured out atm is.
Zero After reset and Trip when I charge.
Reset trip when I run out of EV on long journey.
Deduct Trip from After reset.
After Reset gives Diesel/Hybrid usage
Trip gives EV only usage.

Only issue, I have to make an entry each time I charge, which is every day, which is boring.

 

[supernoodle]

I don't know what year the car is but in 2023 On Board Fuel Consumption monitoring became a requirement. Many manufacturers will have implemented it prior to this though.
This logs the fuel usage for the current (or last) trip and vehicle lifetime.
On HEVs it also has to record distance driven in battery mode, charging, energy used etc.
This info is readable using an OBD2 tool, Mode $09, InfoType$17-$1C. I guess most consumer tools won't support by default, but if you have one of those cheap ELM devices you can send the commands to request that manually.

 

[alexanderfoti]

I don't know what year the car is but in 2023 On Board Fuel Consumption monitoring became a requirement. Many manufacturers will have implemented it prior to this though.
This logs the fuel usage for the current (or last) trip and vehicle lifetime.
On HEVs it also has to record distance driven in battery mode, charging, energy used etc.
This info is readable using an OBD2 tool, Mode $09, InfoType$17-$1C. I guess most consumer tools won't support by default, but if you have one of those cheap ELM devices you can send the commands to request that manually.

I will give it a go. I will check the spec for fuel reporting, but the OBC already reports mpg and ev use seperated out, so suspect it will report the same.

 

[Uncle Benz]

I took my SLK55 AMG out for a hoon, lunch at the Torque Moto Café, then a lovely relaxed scenic drive through the South Downs. I’m glad your day was fun too

 

[alexanderfoti]

I took my SLK55 AMG out for a hoon, lunch at the Torque Moto Café, then a lovely relaxed scenic drive through the South Downs. I’m glad your day was fun too

I'm out in Wales for a long weekend for a family wedding.

My brain wanders whilst isolated in a cottage

My slk amg is coming out tomorrow too, sun finally out a bit

 

[SL63 Mark]

Yes you need to drive a V8 for a bit. It cures all thoughts of fuel economy, I find.

 

[alexanderfoti]

The V12 does that enough for me. Would have done two tanks in it by now.

I just like analysing data. Yes I'm sad.

 

[brandwooddixon]

I think that the only way to compare ICE and EV cars is on actual cost and average that out. So for a commute, the cost of the electricity compared to the cost of the petrol for wherever you most often charge/fill them up.
Electricity tariff can make a big difference, especially if you're left using publicly accessible fast chargers.