Automotive garages and repair shops can be divided into several categories.

Firstly, there are the auto parts stores or motor factors who also maintain service operations. This is not common in the United Kingdom but more common in the US.

A majority of automobile repair workshops are independently owned and operated businesses. These may also include regional or national chains and franchises including OEM car dealership sites. In the US, these sites are commonly certified by their respective manufacturer to perform warranty and recall repairs by that manufacturer or distributor. Independent automobile repair shops in the US may also achieve certification through manufacturer sponsored programs. In the European Union a recent law (The EC Block Exemption Regulation 1400/2002 (October 2003[2])) allows motorists more flexibility in selecting where they can get their car serviced.

Thanks to this legislation maintenance and service work does not have to be done by the main dealer as long as the garage uses Original Equipment ‘Matching Quality’ parts, and are recorded as such, and the garage follow the manufacturer’s service schedules.

http://en.wikipedia.org/wiki/Automobile_repair_shop