Just thought I'd post this info in case anyone doesn't know. It's usually very cheap to add a car to any flight only price on BA or Virgin (or including a hotel). For example there is a flight in November direct to Vegas with BA and the price is about £450 for the flight with 15k Avios points and another £100 if you haven't any points. To add a car only works out at about £50 each (2 people) for 10 days hire, including all fees. When I went in May this year to add a car was just £75 per person (2 people) for 17 days. These prices are based on sale price for flights in November but work on any flight price, whether it is economy or business class, any time of year. Just a few taxi trips can work out more expensive.