The results may be the same, but the routes taken by Iveco and Mercedes-Benz to produce a natural gas-powered van are very different.

While Iveco uses a hefty 3.0-litre diesel powerplant for its gas model, Mercedes has chosen a relatively diminutive 1.8-litre petrol unit – albeit enhanced by a supercharger.

And while Iveco’s Daily is very much a single-fuel van, Mercedes is offering users the chance of dual-fuel usage.

The Sprinter NGT, which goes on sale this summer, will be available as a panel van or chassis-cab in medium and long wheelbases (SWB models aren’t long enough to hold the gas tanks underneath) and can be honed to fit in with individual fleet requirements.

While power is a hefty 156bhp, torque is down on diesel models at 184lb-ft.

Mercedes is fully aware that while some fleets may want to increase their green credentials, many will be suspicious of a new idea and wants to make the transition to gas as painless as possible.

John Reed, Mercedes’ product executive for Sprinter, told Fleet Van: “We want to make sure there is no pain to the purchase and we will be working with potential buyers to adapt these models to the particular needs of the buyers.”

As such, the number of gas tanks under the NGT Sprinter can be varied, so that those who don’t do many miles can opt for extra payload.

Mercedes offers either a 15-litre ‘get you home’ petrol tank or a full 100-litre one, which will allow for 400 miles of use with the conventional fuel.

So why dual-fuel rather than single?

Reed said: “We had a single fuel gas van in 2000 but it just wasn’t flexible enough owing to the lack of a refuelling infrastructure.

"Experience told us that fleets were prepared to make the jump to natural gas but it had to be more flexible.”

The other big difference between the Daily and the Sprinter is that the Mercedes is happy to use either bio-methane or gas straight from the tap.

The downside of using a domestic source is that it comes out at around one bar, whereas the Sprinter’s gas is stored at 200 bar. This means it can take all night to refuel a van.

So would opting for the Sprinter NGT mean a massive investment in a refuelling site for fleets?

Reed said: “Not at all. Our contract hire division will bundle the price of the van and the refuelling cost together and come up with a price. That way we are taking the doubt out of natural gas power.”

NGT models will cost between £4,500 and £6,000 more than conventional models but Reed points out that this figure would be saved on the London congestion charge alone within two or three years.

A conventional petrol model will cost 21p a mile in fuel, while natural gas is 13p a mile. Diesel costs 16p a mile.

Behind the wheel, there isn’t a lot of difference between petrol and natural gas.

Changing fuels is achieved via the flick of a switch and a digital gas tank picture on the dash shows how much fuel is left.

It would have been interesting to try the van fully-loaded on a steep slope as it may well have struggled with such a low torque figure.

But as most vans operated by the type of customer Mercedes is envisaging don’t drive under those conditions, we may be being too picky.

For those who operate the right type of fleet and are prepared to stick their necks out, rich rewards (both environmental and financial) are possible.