I try to put Shell unleaded in my R129 (which only does about 3k miles a year), but my VW Sharan V6 generally gets filled up at Sainsburys (which is cheap and much more local). Last week though I put a tank of Shell petrol (regular unleaded, not Optimax) in the Sharan before towing the caravan 200 miles to Stoneleigh and back. Much to my surprise there was an immediate and noticeable improvement in both performance and economy! Less gear shifting required on the motorway (I doubt I'd have noticed this if I hadn't been towing though), and total fuel consumption (from the computer) of 16.9 mpg instead of the 15 or so I'd normally get in similar traffic conditions. This was despite having the climate control blasting away all the time (very hot weekend). Whilst I accepted that there were probably long term benefits in using 'branded' fuel I wasn't expecting any noticeable difference on the road! PS my R129 handbook just says to use "minimum 95 RON unleaded" fuel, would Optimax be a good or bad idea (M119.982 engine)?