When I take road trips, even on routes where, traffic permitting, I can drive 70-80 mph, my point to point average speed never seems to exceed 50 mph. It's all those restroom stops, fuel stops, lunch stops, etc. And if it's longer than a day trip, my max is 8-10 hours driving (400-500 miles), and then I need to stop for the night. Thus, if a train can consistently perform at a 50 mph point-to-point average speed, it's speed competitive with driving. If it can do 60 mph point to point average speed, it's actually faster than driving. Of course, in order to account for parts of the route with curves and grades, and intermediate stops, etc., the train's top speed on suitable parts of the route will need to be 80-90 mph.