What driving culture are you referring to? The wealthy everywhere have a preference for sports cars. That alone doesn't constitute "driving culture", but a lot of what you're talking about is just compression. The US has much more wide open space than Germany does.
A much more stringent and in consequence structured driving environment. As others have noted, obtaining a license is more difficult. Uncooperative driving behaviour is heavily frowned upon and prohibitions actually enforced: driving in left lane, but also attempts to bully others out of the left lane and overtaking on the right.
As for compression, compare driving in NYC to driving in Berlin.
This isn't to mean that North Americans wouldn't be able to reach this standard if they decided to, but it would take decades.
I guess he's referring to the fact that there are no actual speed limits on "Autobahnen" in Germany, there's a recommendation of ~80mph (130km/h), but itn't a rarity to see people going over 120mph...
To sum up: people drive faster here.
And from what I've heard, it's way harder to get a driving license in Germany (and Europe in general) than in the US.
From discussions with my Dutch friends, I know that it is ridiculously easy and inexpensive to get your driving licence here in Australia when compared to the Netherlands.
I imagine that Germany has very similar standards as The Netherlands, and I could imagine that many US states take a more relaxed approach.
Perhaps this is the "driving culture" to which the parent is describing?
It's also been shown that you can maximize the throughput of a highway if the speed limit is 45mph. Too high, and you need to increase the space between cars.
Although 55mph != 45mph, it's pretty close. It also doesn't serve the individual, but if can't get the cars through fast enough, the traffic will build up eventually.
How was it debunked that 55 saves gas? I'm interested in this, as I sometimes like to drive in such a manner as to economize, and according to my instant and average mpg readouts cruising at or below 60mph consumes far less gas than cruising at or above 70mph.
Right. So is the Autobahn actually all that accident prone?
55 was initially marketed as something that saved gas. After that was debunked, it was changed to "55 saves lives".