>     - I have a US (Cal-spec) stock '88 Vanagon Wolfsburg Ed.
>     - I add the MSDS custom air intake and filter. No big deal.
>     - This van gets me 16-18 MPG on mixed urban / freeway driving
>       in Sacramento, CA. Approximately 185 miles per tankful.
>     - I take this exact vehicle & ship it to Ireland where I'm
>       now getting 25 MPG or a range of 250+ miles on a full
>       tank of gas for mixed rural / urban driving.
>     - No modifications have been made to the vehicle - it's the
>       same as it was in the US.
>     - Just *what* is going on here??!!!

I suspect a different octane and also the bigger gallon.