My 370z is really good on fuel dunno what you people are doing wrong
Firstly dont rely on the display, it lies and secondly , fuel consumption is extremely variably and fluctuates wildly , the only way to get an meaningful comparison is to measure mileage against fuel used ie Fill to Fill and over a considerable time, but who bought their zed to do that ?.
I wouldn't expect a considerable difference between the DE and HR , much more between the Roadster and Coupe and auto and manual transmissions
Dont leave filling up until the range goes blank and you have to slipstream an artic just to make it to the petrol station - it does do wonder for the economy though