Autobahn Speed Limit?

Not likely.  This article compares tinkering with the autobahn speed limit in Germany with changing Social Security in the US. A political "third rail".  This quote is from the New York Times:

"Our politicians like to say that Germany should not have to do more than other European countries on climate change, but in this area, we are doing less,"  said Josef Goppel, one of the few conservative members of Parliament who favor a limit.  For years, speed limit advocates tried to argue their case on safety grounds.  The autobahn, though, is statistically safer than highways in many countries, even if its crashes are singularly horrific.   Saving the planet, it turns out, may be more persuasive than saving lives.

A speed limit on the autobahn will never happen, at least not because of global warming.