The news in today's Autocar scoop that the next-generation 2012 Range Rover will be a massive 450kgs lighter than the current car couldn't be more timely.

A few days ago, the US government declared that the average SUV sold from mid-2016 would have to average 34.5 UK mpg.

Read Range Rover lightens up - full story

Although the formula that is applied to calculate the mpg rating is very complex (it's based on the 'footprint' of a vehicle) and there are some let-outs for building a car that will run on bio-fuels, the result will put Land Rover engineers on the spot.

While meeting the 34.5mpg average will be easy with the combination of a lightweight aluminium body and the frugal TDV6 diesel, building a Range Rover that will meet US market conditions will be harder.