I remember one time on I-15, between LA and Las Vegas, going 95 mph and the traffic was still passing me. Montana doesn't have a speed limit on many roads, so I don't know how Texas could have faster.
Contrary to popular belief, Germany does have speed limits on autobahns. Most of the time it is marked 100-130 kph. On the stretches which have "unlimited" speed limit, you can still be cited for unsafe driving during certain conditions (weather, road conditions, poor vehicle condition to include improper tires for the speed.). Additionally, most insurance companies won't cover damages when driving over 130 kph, no matter who is at fault.