Dont know as im in a diesel Jim but was this with all the seats in tow id of thought it would have been a bit better really but suspect once you hit Scotland the old lead foot may have came out on them lovelly roads.
I think it was a 'lead foot' the whole way up the M6 to the ferry, LOL
Thou I'm starting to read thou the old threads on the Multipla section and there seems to be some complaint about the trip computers idea about economy so I'll fill it tonight and do it the old way
After the service and hoking bits of sparkplug out there should be some improvement I think