wiggydiggy
Guru
That calculation is only valid for a dedicated commuting car.
If you would own a car independently of the commuting use, then only marginal commuting costs are relevant: Parking, Commuting Fuel, and Commuting proportion of service/consumables. Standing charge elements eg Insurance, tax, MOT etc are not saved.
Well reminded and I know Some people might not do it that way.
I used a few different calculators and averaged it as they all work a little differently but some already factor that in, if not I factored that in manually e.g. I calculated my commuting fuel use only, only used the additional insurance charge when I selected 'commuting' as a use for the car.
I did use some other standing charges elements, but as a % of the total. So if I commuted 1000 miles, and my annual mileage was 3000, I'd say it's fair to add 25% of the standing charges to the cost per journey.
Even if I'm out by 100% and the cost was only £10 per journey that's still too high for me now.