Eight cars over the hump and into six tracks. Past the crest there is no throttle — gravity does the pushing and two retarders are the only things you own. A car couples cleanly at or under 4 mph, and how fast it will be going depends on its rolling resistance, which nothing in this yard can measure.
The teal needle is the speed that couples at walking pace; its band is how little is known about the car. The red ceiling is the fastest it can be going and still be saveable. Keep it under the ceiling with F, put it on the needle with J. On a touchscreen, press the left panel for F and the right for J.