I'm playing on a tiny server I host, and if only one character is connected, all work well, but as soon as we're two players, the assist and cruse control doesn't trigger at all.
Ok, this shouldn't happen at all. Are status messaged still outputed to console (i.e. "cruise control activated")? Does this problem occur if more than one person is connected or only if more than one person is riding a car?
Edit: I tested the current version of PDA with another friend. We ran two cars at the same time, driving at 200 kph. Everything worked fine. Are you using other mods?