Altho Transmission has timing and shift point adjustment, it is also dependent on ground speed.
When you hit the brakes, or decelerate and coast, it will downshift as you slow.
Put "REC Automatic Transmission" in vehicle root.
Click Menu, Addons> Automatic to enable.
Click Menu, Addons> Time to set maximum time between Shifts, Floats are accepted. (ie numbers with a decimal point.)
(v2 - Adapted to Cruise Control)"REC Automatic Transmission 3D6.2"
is for REC Basic with Reverse Gear the other one is for older REC with Arcade Style Reverse.