I've said this so many times. Fuel consumption also depends on condition of engine and tyres. When they tested the car, obviously the had the car in super tip top condition and they probably had the Gen 2 port and polished and using the best lubricants, gear oil and also using brand new properly inflated tyres. Also, they probably also have nothing inside the boot maybe just the spare tyres. So to be honest, i'm not really surprised even if they achieved that 17Km/litre. On the other hand, i'm sure you guys Gen 2 is not in good condition as the test car is. Lets face it, some of you guys tyres might not be properly inflated. Some of us don't do regular engine oil change. Some of us drive like in a drag strip.
I don't think Proton is lying but rather its a marketing gimmick. I believe they achieved that figure but they definitely won't tell you how slow and careful and how good the condition of the car is.