very interesting read foca.
Thanks! The Autoexpress was a bit of an eye- opener! i always used to close my windows thinking leaving them open would have a disasterous effect on the drag, abd the MPG (i just leave them open when i want now), and i had my AC removed, i thought it would help the MPG, all round, not just accelerating/ round town (the AC system is 11kgs on the Mondeo, there is a pulley that always turns with the engine, so the AC delete is more than just switching the AC off)
The A.X. article is simplified, and they did not try different tyres (or wirths/ profiles) they tested at a constant 60, 70 and 80, but not at 30 40 or 50, they bundled the overall findings together, without seperating round town/ hill course/ motorway croising (eg round town the AC had a massive negative impact on MPG, but on the motorway at a constant speed, putting the AC on made hardly any difference to the MPG) a heavy weight in the car had a big negative impact on MPG when accelerating, and on the hill course so it depends on the conditions - the results were over-simplified (dumbed down)
Another surprising thing was when coasting up to junctions etc if you put the car into neutral the engine uses fuel to keep ticking over - if the car is in gear it uses no fuel as the ECU cuts the fuel supply - (this is when you are slowing down, coming up to an obstacle, going downhill etc ) - saw this on top gear.
There must be an optimum speed for maximum MPG - it differs between cars but on most cars is probably between 45 - 65 mph on flat ground (depending on gearing etc) - but driving too slowly car rouin your MPG too
If im stopped at traffic lights that i know are going to be at red for a while, i stop the engine, (or stuck in a traffic jam etc)