Juke or V8?

I recently purchased a Nissan Juke 1.6 DigT Auto, and love the vehicle. However the car is consuming way more petrol than indicated on the specs. Friends who drive cars with way bigger engines have less consumption than I do, and I only travel 8kms to work everyday! Was this false advertising on Nissan's part? Dis you just want the sale so you told me anything I wanted to hear? I am deeply upset that I am forking out litres of petrol more than I should be. I looked at specs on the net, and again my car is doing way more than indicated, it's not even in the region of the figures advertised. Could someone please get back to me as I am now considering going to your counterparts at Ford and getting an ecoboost, which will give me the consumption it promises.