"Depreciation" and "capital cost" reflect the fact the vehicle has a maximum life, even given maintenance.

Imagine if I buy a $200,000 Lamborghini which, with regular servicing, will survive 100,000 miles.

That means for every mile I drive, not only am I paying for fuel, and insurance, and tyres, and servicing - I'm also paying, on average, $2/mile in depreciation.

And sure, the "true" value chart might not be linear. Maybe there'll be a sharp drop when the car ceases to be brand new, or a bump in value when it becomes a classic. But so long as it's worth $200k at 0 miles and $0 at 100k miles, the average cost of a mile must be $2.