A Tax Court summary opinion today, involving a driver for Uber and DoorDash, points out:

"We note for the record that the strict substantiation requirements of section 274(d) do not apply with respect to expenses reported to properly used vehicles in a trade or business of transporting persons for compensation pursuant to section 280F(d)(4)(C). However, even in those situations, there must be sufficient evidence to determine the appropriate mileage."

When I look for that statute I find 280F(d)(4)(B), which reads:

(B) Exception for property used in business of transporting persons or property

Except to the extent provided in regulations, clause (ii) of subparagraph (A) shall not apply to any property substantially all of the use of which is in a trade or business of providing to unrelated persons services consisting of the transportation of persons or property for compensation or hire.