The British Vehicle Rental and Leasing Association (BVRLA) is the trade association for the vehicle rental and leasing industry in the UK and states its three primary functions as: 

• To regulate a majority of the industry through a mandatory code of conduct and by regular inspections of members
• To lobby government and its many associated agencies on behalf of the industry.
• To provide members with services and information that aids them in developing their businesses.

BVRLA members run more than 2.5m vehicles and spend some £15.4b each year on buying more than 44% of all new vehicles in the UK. 

BVRLA members also represent 65%+ of the vehicle rental/leasing fleet, 85%+ of the car rental fleet, and 95%+ of the leasing/contract hire fleet.

http://www.bvrla.co.uk