I used 98 for my first re - fueling and kept on using it. My Volvo S40 - which happens to be 'kaput' again! Does not like 95 and as they are basically the same engine I decided to use the higher grade. Also in France, the Octane Rating for 95 is lower than UK; at least at our Supermarket chain.
Intial 'mpg' figure based on 2200 kms of driving is only 33 mpg, but still early days.
