Do I have to install it myself?
No. It's a dependency of Heavy Trucks (Vanilla+) and installs automatically.

How do I make a truck drive itself?
Research Heavy logistics and build truck stops. Open a truck, add stops to its schedule (the "Schedule" tab, like a locomotive's) with their wait conditions, and switch it to Automatic.

Does it work like trains?
Mostly, yes: wait conditions, temporary stops, interrupts, truck groups, and truck limit and priority on the stops. Stops in a row work as one lane.

Can I make trucks pass through a point without stopping there?
Add a truck stop to the schedule with no wait conditions: the truck drives to it and goes straight on to the next one, like a train waypoint.

Do trucks use my roads?
Yes (since 1.0.0), found by themselves, nothing to mark. A road is the space between two yellow lines of hazard concrete, a strip of hazard concrete, or a street of paving (concrete, stone path...) with something else either side: 5 to 12 tiles wide, straight, at least 16 tiles long. Roads from Transport Drones and tiles other mods mark as roads count too. Diagonal roads aren't supported yet.
Turn it off for the whole map in the mod settings (Trucks use roads) or for one truck with Use roads in its truck tab.

My truck drives across country instead of using the road.
It takes the road when one leads where it's going and isn't much longer than driving straight there (at most twice as long by default: Longest detour along roads in the mod settings). Also check that the road is at least 5 tiles wide and straight.

Why are the headlights on / off?
The game only turns a vehicle's lights on with someone driving it, so the Autopilot turns them on itself while a truck is in automatic mode.

Can I filter or limit the cargo slots?
Yes, in the truck window: middle-click a slot to filter it, and the red button next to "Trunk" limits the trunk like a chest.

Does it cost performance?
Only for trucks that are driving. There are no periodic searches of the map, so a big map with no trucks costs nothing.

Will it work with Factorio 2.1?
Yes, it will be updated when 2.1 is out as stable.

A truck got stuck / did something odd.
Please post it in the Discussion tab, with a screenshot or a save if you can. It helps a lot!