with all due respect paul using more of the fuel in the tank will not improve fuel economy - im sure you realize this - so how about you (33Sedan) calculate your fuel economy properly and see how you go...
steps to follow: (taken from above thread i posted)
1. fill tank completely and note kms
2. drive - drive - drive
3. fill tank completely again and note kms
4. to calculate take litres it took to fill / kms travelled