fuel economy and emissions

If my fuel economy is only 19mpg can I go back to the vendor to have it rectified?

I've a problem with the fuel range on a 2008 Toyota Avensis D4-D 2.0 T2. Mileage is 100,000. Until recently when I filled up with diesel I got a range of 620 miles for a tank of fuel; now I'm only getting 590 miles. Can you please tell me what the problem is and how I can sort this please?

All information gratefully accepted.

How economical is the 2010 Audi A6 automatic 168bhp please?

How economical is the diesel 4x4 Hyundai Tucson compared to a petrol one?

I am only getting 40mpg from a diesel Peugeot 407 on long trips; what can be the problem?

What economy should I be getting from my 2011 Toyota Avensis estate? It's a 2.0-litre diesel with 90,000 miles on the clock.

Hello, is it possible to disconnect the stop-start system on a 2010 Volkswagen Passat 1.4 DSG TSI? I find it annoying and I am not convinced it does anything to lower fuel consumption.

What mpg does the Mazda3 saloon 1.6 petrol return?

Which car is best on fuel between 2007-08 Mazda6 1.9, Ford Mondeo 1.8, Toyota Avensis or Opel Insignia please?

How many miles per gallon will a 2008 diesel 1.7 Opel Astra do on average?