if I can prove that that is the maximum achievable,would the Trades Description Act not apply here?

No. The advertised fuel economy figure is well defined. You would need to prove that the car could not achieve the stated consumption on the New European Drive Cycle.

Unfortunately, the NEDC does not reflect average real world applications. But that is not the manufacturer's problem. They are obliged to use that test cycle and publish the figures.

A good improver of economy driving...and i make no accusations or assumptions here as my own driving isn't perfect by any means...is to display the instant fuel consumption reading on the dash display and leave it on, if your car has this feature.

Its amazing how much you can improve your economy when you see just how low the consumption whilst under power is, and how high the figure raises once you lift off and allow the momentum to carry you up to the next junction, full throttle acceleration especially in lower gears will have your eyes bulging when you glance at the reading.

My years on lorries have taught me that terrain and road layout makes an incredible difference, the usual loaded motorway average consumption of 9mpg reduces to 5mpg overall on one particular trip where every single junction/roundabout exits in a long uphill climb...those figure percentage differences are similar for cars.

Still, 30.2 is pretty poor considering the OP says this is the best he can achieve when driving carefully.

A few obvious questions:

- how new is the car, and what's the mileage?

- have you raised your concerns with your supplying dealer?

- are there any Alfa Giulietta forums where other owners complain of poor fuel economy?

There does seem to be a pattern emerging with small engine/turbo petrol engines

What Car? ran a long term Astra 1.6T, only managed 31 MPG. Their 1.6T Focus only managed around 35 MPG, they replaced that with the new 3 cylinder 1.0T and that's strugling to get 36 MPG. Not great figures for modern cars and a mile away from the EU combined figures, which as unthrottled points out, is a test which uses an unrealistic set of parameters, and should only be used as a comparative guide between models.

Ummm it's an Alfa. They eat petrol. I have never seen anywhere that Alfa claims to have any economical cars at all; that's part of their appeal! The cars are stunning and they don't give a monkey's whether they're 'green' or not.

I'm no expert but it must be the type of engine rather than just the size of the car. Oddly enough all three cars in our household (2011 Octavia vRS petrol estate, 2012 Mini Cooper Roadster, 2001 BMW Z3 2.2) are roughly similar in consumption: about 30 in town, 36 on a long run.

That's creditable for the Skoda and BMW, less so for the Mini.