I am not an accountant but it would depend on other factors.
If the cost was just going to be accounted as a general expense and then I would use the first for the sake of simplicity
If the costs were being allocated to different projects or cost centres then I would use the second
The third is not an expense but if you are charging the costs to the client then you could do it this way, It seems as if you are ripping off the client but against somebody might query why some visits seem to be billed at double rate (They will definitely not regard the 55 miles as half rate)
I was going to reply to this the other day but it’s a bit of a how long is piece of string question, 6 of one and half a dozen etc…
As above, if you are billing clients for mileage to/from meetings what have you agreed/what do your Ts & Cs say? Do you even charge clients for mileage or is it just going down as a general expense? If the latter then it doesn’t matter in the slightest what you put as long as you have written down what you want for future reference.
As an electrical contractor for 35 years I tried many methods of charging for mileage.
I eventually settled with including it the price per job based on distance bands from my Base (Office) rather than actual mileage.
However, if you prefer using actual mileage then charge each client from your base to the client, you will win in your example above, but in fairness adjust your mileage charge lower, so it will all average out over time.
That way you will charge the same for each client even if you visit them on different days, or if the clients are 50 miles apart not 10.