Wirelessly posted (BlackBerry8530/5.0.0.601 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)

If you frequently rent cars, I would join one of the foreign airline FFPs, as they tend to have a much better earning rate from car rentals, and there's no excise tax offset to worry about. I regularly earn 1,000 miles in Virgin Atlantic's program for even one-day rentals with Hertz/Avis. And VS miles can be redeemed for travel on many domestic and international partners, with an inter-Island roundtrip on HA available for 6,000 miles in Coach, and 9,000 miles in First, for example.

I have not redeemed any of my VS miles yet, but it just seemed a waste to leave so many miles on the table when renting cars. (And Avis off-airport locations were not crediting to domestic FFPs, but do credit to foreign FFPs.)