Fuel Gauge, Range & Consumption

I've done a search of the forums and found similar threads, but not exactly talking about the problem or problems I think I may be encountering with my new Jazz. For the record, it is a 2009 compliance VTI 1.5L manual bought as a 2010 demo model. I'm told by the dealership that it was made in Japan, sat there, then got shipped here this year.

That said here's the issue...

This is ALL country driving, so a combination of highways at 100km/h-120km/h and then some township driving, so back down to 60km/h and 80km/h etc.

Now during all this driving the fuel consumption indicator on the dash was generally saying about 6L per 100km, in which case one would expect around 650km-700km on a 42 litre tank. The car was filled up before we began and we drove 430km before the fuel light came on indicating that we had about 50km more to drive, drove another 20km before filling up.

To fill up I was only able to put in about 32 litres of fuel.

Next drove another 450km before fuel light came on, drove another 20 kms and then filled up, again could only put in about 32-33 litres of fuel. Drove another 430km, fuel light came on, filled up with just over 30 litres of fuel. So overall when you add what kms I drove and what kms the dash was telling me I could still go, we're looking at 470, 490 and 450 for range and I filled up each time with 32, 33 and 30 litres of petrol.

I asked myself, why is the fuel light coming on when I appear to have so much fuel left in the tank, based on how little I can fill it up with? The manual told me that the light comes on with 7.9 litres left, plus it says there is even a small amount more in addition to that, like a reserve reserve, okay, I understand that... BUT

Why is that my fuel gauge is indicating I'm near E? Shouldn't it show 7.9 L / 42 L, so near 1/4 tank full at that stage? Not near E?

A friend told me they had a Mazda where the fuel gauge indicated the amount of fuel left excluding reserve, i.e. is the Jazz showing me full (42 L of fuel) and then empty when I'm on 10L in reserve?

If it wasn't for the fact that I could only put 30-33 litres of fuel in, which at 450-490 km gives me an economy of 6.5-7.0, I'd be thinking I'm in a gass guzzling V8.

But it is disconcerting if my fuel gauge is showing me empty when I'm at 1/4.

Comments?

I have a vti as well. On highway driving, my trip meter hits 530 before the light goes on.
The fuel gauge goes so fast. I think it's because it's a big gauge, hence more sensitive :).
Try pump up your tyre to increase the economy. Mine is always on 40 psi.
A bit harsh ride, but do well for fuel.

I have a 2004 VTIs manual. I have the tyres pumped to 36 psi all round and use E10 fuel. 90% of my driving is highway at 100 to 110. Last fuel up I got 5.62 litres to the 100km and the fill up before that I got 5.12 litres to the 100km. Prior to pumping up the tyres they were all running at 28 psi. The best I would get was 5.8 to 6 litres to 100 km. pump your tyres up and you will notice a marked decrease in fuel consumption.