Hi Christy,

To be honest, there really isn't much between similarly sized cars powered by the same type of engine and capacity. In that case, the economy achieved is likely to be down to the driver's own style and how much they use things like air conditioning etc. 

One thing to remember here, in line with your mention of a Qashqai, is that an equivalent car will be more economical than a crossover or SUV. So, for 2009-2010, the Nissan Tiida will generally be usefully more economical than a Qashqai with the same engine. The cars are lighter and create less drag through the air.

If economy is your primary focus, keep an eye out for well-maintained cars with narrow tyres and, for 2009-2010, manual models are usually more efficient, too.