I see no point in a “contract” between Hertz and Tesla, if there is no fleet discount. Hertz announced its initial order of 100,000 Teslas, perhaps more, between now and the end of next year. They are already taking deliveries and trumpeting their availability as rentals through Tom Brady ads. Hertz apparently orders Teslas in the same manner as any customer, just in greater numbers. That would also likely be the case for Avis, which gave a subtle hint in its conference call.
Elon’s tweet appears to have been an attempt to remind folks that Tesla does not offer discounts, even to Hertz, while also emphasizing production constraints. Perhaps his understated manner of tweeting was to imply he is not a stock pumper, while he receives criticism of his wealth from CNN and the World Food Program, and Congress is deliberating laws regarding climate change and EV tax credits.