Also was on the Autobahn last fall.... went a steady 190 km/h in a low end rented Mercedes from Dresden to Munich. Lots of fun. Was passed by a pair of Audi A4's going who knows how fast, other than that, I was about the quickest on the road. I guess that makes me a tourist. I'd have gone faster but the Mercedes couldn't handle it, started to shimmy past 200.
In Canada.... took my current car to about 235 on a flat highway west of Calgary, no houses/traffic anywhere around, with great visibility. Just took it up there quickly, then let it go, was in 5th of 6 gears.... apparently it will do 300 but I'm not that crazy.
I was near the roads shown here:
http://www.youtube.com/watch?v=mJF8-PS0ZsY
(those guys were lucky not to get charged after this video, though there was an investigation)