New police cars fitted with secure transportation cells are being trialled in Yorkshire.
Humberside Police has now introduced two specially-modified Peugeot estate cars.
Each car has a prison-style cell compartment, which the force hopes will securely hold detainees while being transported and help keep officers safe.
Senior officers say the vehicles will mean police won't need to call on large prisoner transportation vans in some scenarios.
The cars will be trialled for six months in East Yorkshire, to allow officers to test the cars and see whether further modifications are required before more are introduced into the fleet.
One vehicle will operate on the north bank of Humber river, while the second will be used on the south bank.
The force said the vehicles are now receiving final modifications, before being put into commission towards the end of July.
Matty Wright, Humberside Police's community Chief Inspector, said: “Our fleet is changing to reflect the changing demands of our vehicles and transportation of detainees. These vehicles will enable officers, especially out in our rural communities, to transport detainees in a safe way both for the detainee and the officer.
“These modified cars will mean that officers don’t have to call on the larger prisoner transportation vehicles to bring people into custody and are a good vehicle to bridge the gap between our traditional squad cars and the prisoner transportation vans.”
The cost of a new standard police car stands at about £16,000, according to Humberside Police.
The force said two ex-demo modified police cars costs just £20,000.
They were modified by Peugeot for the police and further alterations were made by the force's own mechanics.