fuel aconomy on my pajero 91 petrol

hi guys thought i,d give same feed back on my experiment with the fuel aconomy on the paj with the tank being filled up to the right level on both occassion .with the first tank taking on 78 ltrs for 677 k,s with unleaded and then with bp altimate on the second tank i got 665 k,s when the petrol light came on and this was all around town driving .i noticed the diference in power whole i was using bp altimate i just had that little bit more than normall , just fitted arb roof rack fitted and tinted windows done all i need now is same red sand under my feet and i,ll fill right at home cant wait to head north cheer,s peter