Police patrol cars will now come from only four manufacturers, helping to cut down costs of more than £3.4 million every year.
Beat officers will just choose from selected models donning national livery and coming ready with technology, signature blue lights and safety equipment.
Other duty members will have to choose vehicles from 18 categories with 25 suppliers.
The move will also mean that the police department will be looking for cheaper car insurance to help with cost-cutting.
The police force annually purchases as many as 5,600 vehicles from a range of manufacturers, which leads to an overall cost of around £83 million.
With the new decision, hundreds of vehicle options now fall into 18 categories and 25 suppliers.
Beat car options include Ford Fiesta or Focus, Vauxhall Corsa or Astra, a Peugeot 308 or two models of Hyundai.
For high performance traffic vehicles that are usually for patrolling motorways, there will be a choice of BMW (530 diesel), Audi (A4 or A6 three litre diesel) or Volvo (V70).
Other secondary vehicles such as motorbikes, vans or armoured VIP saloons will be supplied by manufacturers including BMW, Volvo, Jaguar, Iveco, Honda and VW.
David Horne, of the National Police Improvement Agency (NPIA), said: "Through collaboration, we are able to standardise how police vehicles are used across the UK, which means further efficiencies are possible in areas like training and mutual-aid."
© Press Association 2010