With news of the VW emissions-rigging scandal breaking within two weeks of US journalists first driving Range Rover and Range Rover Sport diesel models, the timing could barely have been worse. Particularly in a passenger-car market where diesel remains a niche proposition, accounting for less than 10% of sales compared to a near 50/50 split in the UK. With cheap fuel and an already sceptical public being repeatedly fed negative diesel headlines, the omens don’t auger well.
Nonetheless, the premium diesel SUV market has grown by 29% in the last six years in the US, with Land Rover’s German rivals all benefiting. Those rivals unanimously field singe-turbodiesel six cylinders, despite having twin-turbocharged alternatives at their disposal.
‘Vehicles are tested to around 4000rpm for EU emissions tests, but American LEV tests are conducted throughout the rev range,’ a Land Rover engineer explained. ‘A single turbocharger simplified things for our first US diesel, and it was clear that the German brands had taken the same path.
Land Rover has invested heavily in taking diesel to the US. The revised TDV6 engine maintains the previous twin-turbo set-up’s 254bhp and 440lb ft, while promising 40.9mpg and 182g/km CO2, improvements of 3.2mpg and 14g/km respectively. A ball-bearing single turbo, two-stage oil cooler, revised fuel-injector nozzle and low-pressure exhaust-gas circulation all contribute to the efficiency.
And while those costs can be spread across the roll-out of the engine in numerous markets, including Europe, the US-specific testing programme has not been cheap: the US test fleet covered a million miles over a year-round schedule that spanned everything from sub-zero winters to 49deg C summers; even the TDV6’s eight-speed gearbox was recalibrated to better suit typical US driving conditions.
Land Rover had predicted diesel would account for 15-20% of its US Range Rover and Range Rover Sport sales – perhaps more in Canada – helping bean counters justify the scale of the development programme. How that plays out in light of recent events remains to be seen.
But if US consumers can put the black cloud of the VW scandal behind them, early signs are they’ll enjoy the TDV6: in customer trials, all drivers had to be told they’d just driven a diesel.