In the US, business auto deduction is around 52 cents per mile.
An oldish paid-off relatively inexpensive car will absolutely do better than that on average. But it's actually not unreasonable that the business deduction bases costs on something like a late model leased midrange sedan like a sales rep might use to drive clients around.
Accounting for depreciation, interest, insurance, actual service bills and petrol, I ended up with A$0.25 per km and A$4150 per annum, so ATO-sanctioned business travel compensation always rightfully seemed to be a handout to me.
A new BMW can easily cost 6x as much, hence "average body temperature".