Only about 25-30% of per-mile costs are fuel.
Depreciation is the biggest component, and that is driven by mileage. My recollection is that the GAO/IRS rates are based on midsize sedans.
Three years ago, the average Uber driver made about $0.80/mile according to survey data. You can argue that the costs vary from $0.50/mile and $0.70/mile, but either way the driver is pretty fucked and is selling their asset’s value as well as time. Rental car companies price dynamically based on fleet depreciation in near real-time… there’s a reason why Uber didn’t buy 10,000 Priuses.
The car is a sunk cost, but the mileage and wear and tear erodes the value of the asset.
This is when amortizing the full cost of the car. Depreciation due to age, insurance and the whole lot. But these are sunk costs for someone who already needs a car for unrelated reasons. Any of those people are rational to consider only the incremental cost from the additional miles and fuel.
And that number is also assuming the typical car owned by people in general, not the typical car used for ride sharing. The most common "car" in the US is a Ford F-150. The most common Uber is a Toyota Prius. Because people aren't as dumb as they're made out to be.