I stumbled upon this site while looking for info how to make my smart Roadster more fuel efficient at highway speeds. For those who don't know about smart Roadster here's a good article about it (
http://www.carpages.co.uk/smart/smar...1_07_02_04.asp) . The car in the pictures is similar to mine except for the wheels.
As you can see from the pictures the shape of the car body is far from optimal aerodynamically and I quess there's quite a bit to be done to drop the Cd value from the stock 0.40 to more acceptable level. As standard the fuel consumption rises quite dramatically at speeds over 100kph and at the 120kph, the legal top speed on motorways here which I do a lot, the fuel consumption equals that of a much bigger and heavier car. For comparition the best result I ever achieved was 3.8L/100km @90kph while closely trailing a semi truck on motorway and normally @120kph the consumption rises to nearly 7 liters per 100km which almost halves the mileage compared to my best achievement.
Where should I start? Which mods should I expect to achieve the best result at least effort and cost? Vortex generators, side skirts, front spoliler??