In an extreme engineering validation test, they set off from Land Rover's UK home at Solihull to drive the 16,800km extended Silk Trail, arriving in Mumbai, India, 53 days later. The mission took the vehicles through Europe and into Central Asia, passing the mythical Silk Trail cities of Bukhara and Samarkand on their way to the ultimate challenge – the Himalayas.

In the high altitudes of the Tibetan plateau, the Range Rover Hybrids entered a technical unknown. Pushed into thinning air at 5,000m, the reduced atmospheric pressure challenged engines and cooling systems, and the Land Rovers’ occupants too. More than a third of the 14-strong group suffered headaches, and two needed bursts of oxygen. But the Hybrids revealed an advantage. Their electric motors were able to counter the efficiency-diminishing effects of low oxygen faced by internal combustion engines.

On arrival in Mumbai, these heavily laden, hard-driven Hybrids returned an impressive 15.5-15.7km/l (36-37mpg), confirming that the Range Rover Hybrid is as robustly tough as any other Land Rover – a magnificent off-roader ready to take on any challenge.