Might be the same as in Germany - they're using the Research Octane Number instead of the Road Octane Number to make it sound like they're selling 'higher-powered' gas - here our octane values are 93, 95 and 98 across the range of fuels (or 100 if you use Shell V-Power Racing), but it's more or less the same as you have in the US. Just mention to your tuner what brand you use and he/she should be able to tweak it for you accordingly.