It has been an arresting sight on Shropshire’s motorway for a fortnight, but police today admitted they were barred from chasing speeding motorists in their on-loan 168mph Lotus Evora.

Officers took up position behind the wheel of the luxurious £50,000 sports car in order to patrol the 450 miles of West Midlands motorway – including the M54 and M6 – during a two-week trial which came to an end on Friday.

But Constable Steve Rounds, from Central Motorways Police Group, has now revealed a contract stopped officers putting their foot to the floor in the turbo-charged sports car.

Constable Rounds said: “Part of the agreement we had with Lotus was that we would not use it to pursue other vehicles. We have all been driving it very carefully.

“It has really been out there to enforce the message that we are watching for speeders and are on patrol, but it is not a practical police car.”

Despite the “no chasing” rule, Constable Rounds said the campaign had been very successful at raising awareness of road safety.

He said: “It’s been really well received, even in areas that are not what you would typically view as police-friendly places.

“We have had a great response with people pointing and taking photos.”

Constable Rounds added that forces across the country were impressed with the impact the Lotus had made.

South Yorkshire Police is using the car for a safety campaign in Sheffield.

“The trial has had a huge impact and although we are essentially a local policing organisation based in the Midlands, the motorists we deal with come from all over the country,” he added.

“National news coverage has let us reach those people and let them know we are patrolling the motorways in our area.

“It has sent a message and highlighted our safety messages because of the interest it has generated.”

Lotus loaned the car, equipped with a 280bhp 3.5 litre V6 engine, free of charge. The firm also paid for its police markings, badges and flashing lights.

A Lotus spokesman said the West Midlands trial had been very successful but declined to comment on details of the company’s contract with police.

By Danny Carden