KEY POINTS:
Sure, it's easy driving and some pretty slow running, but on a recent Chicago-Detroit economy run, Mercedes-Benz's Smart Fortwo and E-class Bluetec diesel models made impressive fuel economy figures.
The Smart Fortwo CDI managed 3.9 litres per 100km over the 4400km route, and even the luxurious turbo-diesel Mercedes E320 CDI Bluetec consumed an average of 5.8l/100km.
The journey from Smarthouse in Venice, a district of Los Angeles, to Detroit took seven days.
A large part of the road trip saw the test convoy, consisting of one Smart Fortwo micro hybrid drive (MHD), two CDI versions and the E320 Bluetec, travel along the legendary Route 66. Media representatives from Germany, Italy and America took turns at the wheel.
America is not renowned for its high-speed open-road driving, but the convoy still had to cope with a few mountain passes and busy cities.
There was also a severe spell of winter weather, with fresh snow and temperatures of down to minus 15c.
With its 52 kW 1.0-litre petrol engine, the Fortwo MHD achieved 4.8l/100km. Its start-stop function uses the idling phases to shut the engine at traffic lights, level crossings or in stop-and-go-traffic.
