407 SW Platinum 2.0 HDI Consumption

Hello Yours have given me a demonstration car 407 SW a month ago. The car is BJ 06/ 2005 and now has 8,000 km on the clock. I now have a question about consumption. I drive half city traffic and the other half country road, whereby I am currently paying attention to keeping the consumption low (indicated on-board computer). Nevertheless, the consumption is on average 9.2 l. Is this normal? When I drive at a crossroads, the consumption goes temporarily to over 30 l (in words thirty l. But the number of 2500 tours is rarely exceeded. Who can tell me about his experiences or give me tips? I am happy about your hopefully numerous contributions. Ulli