The next Ford Focus RS is highly likely to have a potent diesel engine as well as a petrol unit, Autoblog has learned. Ford of Britain sales director John Wellsman has told us he believes a diesel option would 'double sales' of the car in the UK.

'A diesel version would work very well in the RS,' Wellsman said. 'Running costs were expensive on the outgoing RS – especially fuel – a diesel would change that.

'The RS would have to be three-door in my opinion – it needs to look different to the range. The prospect of the RS gives us a lot to look forward to.'

Although no official announcement has been made on the forthcoming RS, this news will excite the brand's 550 dealers. The last one was a huge success, especially the special edition 500 which had five times the number of orders that Ford of Britain had cars for.

'We had to allocate cars and disappoint potential owners,' said Wellsman. 'But that shows the demand for RS models.'

However, many RS owners have chopped in their cars early after experiencing huge bills. At one dealership we visited recently two 59-plate customer cars were for sale on the used forecourt. Both had been exchanged because their owners couldn't afford the running costs.

'A diesel engine that offered similar performance to the petrol unit is just what the RS needs,' one dealer told us. 'The diesel engines are now really drivable and other brands have done well with performance versions, like Skoda and its vRS. I think a diesel is a great idea and would sell very well.'

Nigel Sharp, Ford of Britain MD, added: 'The last RS did very well. We were delighted with it. Especially the RS500 – that sold out in days. We had to allocate them to dealers. We are very excited by the prospect of another RS.'

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