The hybrid Range Rover and Range Rover Sport are powered by a diesel engine alongside an electric motor rather than a petrol unit – even though the leading markets for hybrids are the United States and the Far East, where the appetite for diesels is small.

‘There are a couple of reasons why we decided on a diesel,’ said Peter Hichings, Jaguar Land Rover's director of hybrids, to news agency Headlineauto. ‘We wanted to make the hybrid the most fuel-efficient Range Rover and we wanted it to be Europe-biased. We see a real opportunity in Europe. The technology is adaptable to petrol engines, but there are no current plans.’

Hichings also explained why the cars have not adopted the plug-in hybrid technology Land Rover has been working on.

‘The world isn't ready for plug-in hybrids,’ he said. ‘There isn't the infrastructure to recharge them, and a plug-in hybrid which is not plugged in regularly is hopelessly inefficient. But the technology is fully developed and we can be ready when the market is ready.’

The hybrid Range Rovers pair Land Rover's 3.0-litre, 290bhp V6 diesel engine working with a 46bhp, 170Nm electric motor housed within the eight-speed automatic transmission. Land Rover claims comparable performance to models powered by the TDV8 diesel engine, but with 26% lower CO2 emissions (169g/km) and average fuel economy of 44.1mpg.

The triple-mode drive system defaults to full hybrid mode, but drivers can switch to zero-emissions all-electric (EV) operation or a sport setting, which gives stronger acceleration. EV mode allows one mile of electric driving at speeds of up to 30mph before the batteries are exhausted, but they are recharged when the driver coasts or brakes. EV mode ensures both cars are exempt from the London congestion charge.

Creating them posed several challenges, said Hichings.

'From the start we said they were going to be hybrids and they were going to be Range Rovers, but there were not going to be any compromises,’ he explains. Passenger and luggage space in both has been maintained by mounting the lithium-ion batteries in a boron-steel cage beneath the floor.

‘That was the first challenge – the package,’ said Hichings. ‘The second was to make it work, to be durable and to be as good off-road as any other Range Rover. The third was to ensure the two power systems would switch seamlessly.’

There was also the issue of preserving the cars' ability to wade in water up to 900mm deep with batteries mounted beneath the floor.

‘We have not isolated the batteries completely,’ commented Hichings. ‘They are going to get wet. But we spent a great deal of time and trouble on the seals. We took the cars to all the places we normally go to and tested them for tens of thousands of miles to make sure they are proper Range Rovers.’