It believes this is due to more fleet operators deciding to adopt a wholelife cost approach, which factors in all of the costs associated with running a vehicle over its lifetime (also referred to as total cost of ownership (TCO).

“The move to reintroduce petrol vehicles on to the fleet has gathered momentum as more companies take a wholelife cost approach to their fleet strategy,” says Bushnell.

“At Arval, we took this step during 2008. However, it is still a ‘slow-burn’ and is certainly not widespread across the market.”

Lex Autolease is also encouraging its customers to use wholelife costs.

“It’s the best way to run efficient vehicles, along with CO2 management,” says Chris Chandler, senior consultant at Lex Autolease.

“When using wholelife costs, Ford’s Ecoboost technology can fight on a level playing field with diesels,” he adds.

Fisk agrees: “Using a total cost of ownership methodology, the small, efficient petrol engines are holding their own against diesel equivalents.”

She suggests that the cheaper cost of petrol, combined with the generally lower acquisition costs, offsets the higher employer’s national insurance and lower mpg achieved on typical petrol cars.

However, this is not the case with medium and large-sized fleet cars where the diesel fuel-efficiency outweighs the petrol savings.

FleetCor, whose main trading brand in the UK is the Allstar fuel card, believes that more organisations are basing their vehicle selection on wholelife costs.

Brian Flood, vice-president of products at FleetCor, says: “We are starting to see a re-emergence of efficient petrol vehicles on fleet selection lists.

“This is still in its infancy as can be seen from Allstar’s fuel purchasing figures which show a 86%/14% split in favour of diesel.

“It is worth noting that from a wholelife cost perspective, a petrol vehicle doesn’t have to have a lower fuel cost to earn its place on an organisation’s selection list.

“In fact, it could have a slightly higher cost of fuel, but this could be countered by improved depreciation and maintenance costs.”

Some fleet operators that have diesel-only policies are willing to consider petrol.

Debbie Floyde, group fleet manager at Bauer Media, says: “Petrol is viable and I will consider it, depending on the circumstances.

“If an individual approached me about having a petrol model and the wholelife costs stacked up I would allow it.”

However, she points out that it is usually easier to reallocate a diesel model.

Flood agrees: “Alternatively-fuelled vehicles may be harder to reallocate to staff.”