I googled that at 2790 miles, but even if it was that short, we're talking about an average of right at 105 miles per hour. That's counting in fuel breaks.
I watched a youtube video about some of the runs a while back. IIRC the one team said they were topping 190 through some sections (western states), and that their "nominal" speed was in the 140 to 160 range. They had improved both horsepower and cooling in their vehicle. They had doubled the fuel capacity and the ability to refuel (twin tanks, twin fillers). They had radar detectors and night vision and support staff pre-positioned out in front of them reporting on traffic, LE, weather, etc.
To make the run and be competitive it is now a big undertaking. Lots of $, lots of people, serious equipment. It's not just a couple of yahoos with a muscle car they bought at auction and a cooler full of energy drinks...