Wow, the game also acts as if there were no controls whenever I try to control my car or motorcycle with NPC in nearby seat. So I can start it and even control but only when NPC is outside. Once she takes nearby seat - my character drops controls and I get hit by moving vehicle! I’ve seen a message that vehicle is too heavy for the engine ( I modified the car a lot) but non-modified motorcycle with 2 seats acts the same. And is not too heavy when I ride it alone.
Update: I’ve swapped V6 engine to V8 one. There is no message about vehicle being too heavy for the engine now, but I still cannot ride it together with NPC. Looks like a real bug now.