Your proposed test doesn't take account of how much fuel the vehicle uses under normal throttle conditons

It might not be as far off as you might think. If you plot fuel economy vs speed, the economy follows a skewed "n" shape. It is always poor at low speed, peaks between 35 and 50 mph, then starts falling again as air resistance takes over. Most cars get similar fuel consumption at 30 mph as 50 mph (each speed is on the opposite side of the peak), so the single figure at 50 mph is actually quite useful.

What I would really like to see is manufacturers being forced to publish a full BSFC map with a curve of road load at various speeds superimposed. This might be a bit complex for thickos to comprehend but why should the lowest denominater always set the standard?

This way we could see if the new eco-variable-intelligent engine is really that much more efficient than the old one!

Accelerating weight costs you!

Agreed. That's why I put one single 0-60 in there. The problem with simulated cycles is that they are both complex to operate and still don't give tell you anything useful-there are just too many variables-which is why i think simulated cycles should be scrapped altogether. If you look at the urban section of the NEDC, there are a lot of gentle accelerations, followed by gentle decelerations to a complete halt. A good driver can largely avoid completely stopping-even in urban conditions-by anticipating the road ahead.

I'm not really interested in the aggregate fuel consumption of say ten 0-30mph-0 cycles because the figure is more dependant on the cycle than the car.

The beauty of measuring consumption at a steady speed is that it gives you a number which is meaningful-and useful in the real world. It is also much harder to massage fuel consumption at a higher speed.

There is a definite need for a proper cold start-both emissions and fuel economy plummet when the engine is very cold. A 20-25C cold start is warmer than 90% of the cold starts that your average driver will encounter.

I would also argue that there is a need for a full throttle acceleration event so we stop kidding ourselves that cars only produce 0.05g/km of particulate matter or whatever the Euro V figure is. Petrol engines (especially turbos) run rich at WOT and this is never encountered in the NEDC. Diesel engines shut off EGR at full load and NOx levels rocket.

That's not fair on the OEMs. The test cycle is mandated by EU law-set by politicians. A lot of OEMs saw how hopelessly flawed the legislation was-particularly with respect to the banding of CO2 tax brackets as oposed to a sliding scale. This was always going to encourage cycle tuning. The politicians interferred with something they did not understand and the blame lies entirely with them.

http://www.fordownersclub.com/forums/topic/11781-how-do-they-arrive-at-those-official-fuel-consumption-figures/page__p__76783__fromsearch__1The The official figures test.Best i've got from the Focus 1.6 TDCI =54.4 miles to the Gallon.As said before car manufactures will be reluctant to change the system which suit them.