"That's because hydrogen is the most challenging in terms of fuel production, vehicle technology and infrastructure deployment".
The next step would be to figure out what this would mean in terms of fuel economy.
The results are satisfactory in terms of fuel consuming and efficiency of ultracapacitors and batteries.
The latest "2ku" technology employs satellites, with more compact and aerodynamic antennae on planes than previous versions, lowering the operating costs in terms of fuel burn for airlines.
Crossover utilities are similar to these vehicles in terms of emissions and often slightly worse in terms of fuel economy, because their high roofs give them poorer aerodynamics.
The smaller the gap between the back of the cab and the nose of the trailer the better off you are in terms of fuel economy".
Currently, he said, "You're trying to force everything through a few pipes, which is costly in terms of fuel burn and could hinder range".
Petrol-electric hybrids, powered by both a standard internal-combustion engine and an electric motor, are catching up in terms of fuel economy and carbon emissions.
"We needed to get back into a position that we could be proud of in terms of fuel economy," he said.
Superior in terms of fuel consumption, range, exhaust emissions and running costs; they were the environmentally-friendly fuel of the future while petrol was the endangered species.
"Diesel clearly offers benefits in terms of fuel economy and for many customers fuel economy is an important thing," he said.
