The road to a more environmentally-friendly form of commercial vehicle transportation is littered with side turnings and dead ends.

In the past 10 years we have seen LPG, CNG, biofuels, electric power and bolt-on hybrids appear.

But none has so far proved a credible and cost-effective alternative to the diesel engine.

Now, at last, a viable solution is on the horizon – and the great news is that this new vehicle has been designed and built by Britons in Britain.

The Emerald t-001, which is due to go into full production in 2014, is unique in the world of LCVs. It runs on an electric motor, which is supplemented by a small diesel engine when the power gets low, thus solving the age-old range problem that dogs full-electric vans.

But the difference between this and other hybrids is that the diesel motor doesn’t power the wheels – it is purely there to maintain battery charge to power the motor. It kicks in when battery power gets down to 25%.

The sad news is that the vehicle is likely to end up being built in America, to be ‘flatpacked’ and sent to assembly plants in various European countries.

So far in tests, the van has returned 232mpg and more than 400 miles on a six-gallon tank of fuel, while emitting just 31.4g/km of CO2.

However, the fuel consumption is likely to be much higher than the test cycle figure over a full tank given six gallons and 400 miles equates to 67mpg, including its plug-in charge.

Payload is 1,400kg and load volume is 5.2 cubic metres. It is expected to gain a five-star rating in Euro NCAP crash tests.

The Emerald is the culmination of three years’ work by two companies, Revolve and IE-LEV, and has been partly funded by the Government’s Technology Strategy Board.

Revolve built an aluminium chassis for the van and made all the panels from plastic rather than metal. It then sourced front and rear suspension, differential, brakes, steering and cooling and heating systems from the Ford Transit, together with a 1.4-litre diesel engine from the smaller Fiestavan.

Other parts come from British companies Multimatic, Axeon, Eve-Electric, Ricardo, Penso, RDVS and Umeco.

In an interview with Fleet Van, Emerald Automotive chief executive officer Andy Tempest said: “We have only built two of these vehicles so far and would love to put them into full production in the UK as they have been designed, sourced and built here.