Don't bother to compare Octane Ratings from different countries, or from different time periods. They are measured differently. We get 87 R+M/2, which is about 90 measured the old way.

Anyways, the new cars can go over 10:1 because of the superior engine managment systems (fuel injection, lambda sensors, and most importantly: Knock sensors). Don't try this on your old carbureted cars, kiddies.