In an attack on police force waste, the PM criticised the cost of back-office functions in Greater Manchester police. Among other things, he picked on the 106 vehicle fleet maintenance staff.
Here's a thought, Dave: if the police used fewer vehicles, they'd not only save on fleet maintenance and vehicle cost. There'd be a benefit to the environment, and some research indicates that bobbies on bicycles are more effective than car-bound cops. Pedalling police are also more approachable than squad-car officers.