Good question, Phil. Here's the median case, with the average number of cars on the road each quarter.
Q4 '26: about 1,100 Tesla-owned
Q1 '27: about 2,200
Q2 '27: about 4,400, plus the first 700 or so customer-owned cars
Q3 '27: about 8,800, plus about 7,500 customer cars
Q4 '27: about 17,500, plus about 32,000 customer cars
Tesla's own fleet roughly doubles each quarter, and customer cars join from Q2 '27, with Tesla keeping a share of their fares. Paid miles per car rise from about 90 to 140 a day, while fares ease from about $2.00 to $1.65 a mile.