The King of the Road challenge in Forza Horizon 6 is a weekly set of four tasks tied to the Autumn playlist, and all of them must be done in the same car. Everything centers on the 1989 Nissan Silvia K's, so the first thing you need to do is get that car into your garage before touching any of the objectives.
Get the 1989 Nissan Silvia K's first
The Silvia K's is the required vehicle for every part of this challenge. It is available to purchase from the Autoshow, and it can also show up as a race reward. It is not an expensive car, so the fastest route is simply spending the credits and buying it outright rather than waiting for a drop.
Once it is in your garage, switch to it and keep it as your active car for the entire challenge. None of the tasks count if you complete them in a different vehicle.

King of the Road tasks and requirements
The four objectives are listed below in the order they make sense to tackle. The first is essentially free, while the rest take a little driving skill.
| Task | What you need to do |
|---|---|
| Drive the Silvia K's | Get into the 1989 Nissan Silvia K's, then drive to the nearest Horizon festival site. |
| Earn 3 stars at Drift Zones | Enter any Drift Zone and score high enough on the star rating to hit three stars. |
| Win a Road Race | Start any Road Race on the map and finish in first place. |
| Festival Kilometer Drag Meet | Complete two runs at the Festival Kilometer Drag Meet. |
Earn 3 stars at any Drift Zone
Open the map and pick any available Drift Zone. There is no specific one you have to use, so choose whichever is closest. Each Drift Zone rates your run with stars based on how cleanly and consistently you drift, and you need a score high enough to land three stars.
The Silvia K's is well suited to this thanks to its drift-friendly setup, so focus on holding long, controlled slides through the corners. Remember to stay in the Silvia, since the score will not count toward the challenge in any other car.
Win a Road Race
Select any Road Race marker on the map. The Silvia K's handles this race type comfortably, and the only requirement is finishing in first place. If the AI is proving too quick, drop the difficulty in the settings before you start so the win is easier to lock in.

Complete two runs at the Festival Kilometer Drag Meet
The final task takes place at the Festival Kilometer Drag Meet, which must be unlocked before it appears on your map. If you do not see the event marker, it has not unlocked yet, so progress through the area until it shows up.
Once it is available, all you need to do is complete two runs in the Silvia K's. Winning is not the requirement here, just finishing two runs. For a cleaner launch, hold the handbrake, activate launch control, and release at the final light.

Common reasons a task does not complete
If progress is not registering, the cause is almost always one of two things. Either you are driving a car other than the 1989 Nissan Silvia K's, or the Festival Kilometer Drag Meet has not unlocked yet for the drag runs.
Finish all four objectives in the Silvia and the King of the Road challenge will clear for the week, adding its progress toward your Autumn playlist completion.