I've got the 1.4iDsi Jazz (the 1.3 everywhere else) and I started out the tank really trying to use the techniques described here, espescially the coasting downhill and driving slower 90-100km on the freeway) and even drafting behind trucks!

...but I must admit that after a few days I found myself speeding to work when I was late (150+km/h) and enjoying a few corners and overtaking with glee. Then I had a stern word with myself and settled back down into a more reasonable compromise between cautious driving 90ish to 120km, but still coasting downhill in neutral and in under engine breaking to traffic lights, etc.

My onboard computer read 6.1l/100km before I filled up (at the same pump as last time - 95unleaded)
Well, I must say I'm thrilled with my mileage - 35.15litres and I travelled 619km giving me 5.68km/l or 41.42mpg!!

What surprised me is how off the onboard computer was. I filled exactly the same (first click on the pump), same time of day, similar weather and temp...did I do something wrong?

I suppose I should just check the next tank...

I must say that it's such a pleasure having the Jazz...10 days between fills and less than half the price over my previous car!

Cheers,
Glenn