Last week in San Francisco I rented a compact car one way from Fishermans wharf to SFO airport. Over the phone they told me it was a $25 surcharge, but I was only charged $98 with tax for the two day rental.
When I tried using points they wanted around 3K points...which only knocked $50 off (one day of the rental). It wasn't worth blowing 1/3 of the points that took me a year of heavy travel to earn.