[s-cars] Interesting state re: fuel consumption

[Tony Curran]

Since changing summer oil from Mobil 1 15W50 to Elf 5W40 three weeks ago,
I've been getting an extra 20 to 30 kms extra per half tank. Just filled up
and got 310kms from 37 litres - close to 12 litres per 100kms (or 20mpg).
 
Mostly city driving and this week with roof bars and boat carrier on top
(sometimes with the boat too)
 
One of these...
 
http://www.filippiboats.it/photogallery.asp?s=4
<http://www.filippiboats.it/photogallery.asp?s=4&id_599=1&Id_600=10>
&id_599=1&Id_600=10
 
Any thoughts on that?
 
Tony
96 S6