i have recently bought 2002 - scenic 1.9 dci and average diesel consumption is 9.5 l/100km or in uk units ~25 mpg.
That is quit a lot reading yours post.
Is there something wrong with my car or with my driving (in town 3rd gear with 2.000 rpm about 32 mph)?
On hi-way consumption is 36 mpg (with air-condition).
What should i do, where to look 4 a problem?
Very late coming back to this, but two things to think about.
First is that (as commented above) you may be using the fuel consumption as reported by teh car; since that assumes the fuel flow is happening all the time your injectors are open, having partially blocked injectors would give very poor reported consumption figures without having poor performance or even actual poor consumption.
So do a journey from full and reset trip (doesn't need to be long) and then top up again at the end. Compare with the trip meter for the same journey. Volumes should agree, and so should consumption.
So, when you find that the reported value doesn't agree with the actual values, then you will be read to have the fuel system cleaned out.
I have used Redex Diesel Advanced (UK name; search Amazon for "REDEX DIESEL ADVANCED 500ML") as my cleaner of choice; put a bottle into a tank of fuel, and you will get performance improvements almost immediately (within 100 miles) and definitely have a benefit by the end of the tank.
(Note there is a similar named treatment for the Petrol injector system, which I have also used to good effect.)
Do not confuse these treatments with the normal Redex (put a shot in with each tank, as upper cylinder lubricant)