What is the best first step for How to fix poor top speed in Forza Horizon 6?
Poor top speed is not only about adding horsepower. Final drive, aero, tire drag, class limits, and whether the route actually rewards top end all matter.
Check if the route needs top speed: what should I do?
A highway test can make a race tune worse. Tune top end for the longest useful straight in the target event, not an empty-road fantasy.
Use gearing before power upgrades: what should I do?
If the car already has enough power but runs out of gear, more horsepower may only create traction problems.
Balance aero against straight-line speed: what should I do?
More downforce can make corners easier but cap the car on long straights. Less aero can make fast corners worse even if the speed number improves.