the new record holders averaged 193km/h when crossing “several” States. It is unknown what car the new record holders used.
What is known is that they were well prepared, with over 30 spotters littered across the country, along with a heavily modified vehicle.
From a 2015 AMA
with the man interviewed in the article:
Mercedes generally complies with the German agreement to not build cars that go faster than 250 kph/mph. The CL has a speed limiter that actually cuts the fuel around 158 mph. We hit that many times.
I looked into some ECU files that would remove it but they are aimed increasing power. That tends to decrease fuel economy which I couldn't cope with in this challenge.
In hindsight it was actually helpful to not be shooting for 170-180 mph due to the fact that the exhaustion of driving goes up exponentially with speed. You end up trying to slow down to decompress. We kept it at 125-145 most of the time and that worked well.
We had scouts in PA, OH, MO, NM, and CA. They ran about 100-150 miles ahead of us and reported back based on police activity, weather, and traffic. Fortunately the coast tended to be pretty clear. The scout cars were very helpful in increase the confidence that you need to drive that fast.