what is the fastest car in forza horizon 4

[LeLawson]

The fastest car in Forza Horizon 4, in terms of pure top speed, is the Mosler MT900S. This track-focused hypercar can consistently hit a top speed exceeding 270 mph (435 km/h) when fully upgraded and tuned correctly, making it the undisputed king for speed traps and highway runs. Its dominance is due to an exceptional power-to-weight ratio and aerodynamic profile that minimizes drag at extreme velocities.

While the Mosler holds the top speed crown, "fastest" can depend on the context. For a standing mile, the Koenigsegg Agera RS is a fierce competitor. For circuit racing, cars like the Shelby Monaco King Cobra or the Ferrari 599XX Evolution often post quicker lap times due to superior handling and acceleration out of corners.

Achieving these extreme speeds requires more than just owning the car. You need to install all the top-tier upgrades, especially the X 999 performance index conversion. A proper tune is critical; this involves adjusting the gear ratios for longer top-end gears, fine-tuning the aerodynamics for low downforce, and optimizing the tire pressure for high-speed stability. The dry, flat motorway on the mainland's east side is the best location for top speed attempts.

Car Model	Max Verified Top Speed (mph/km/h)	Best For	Key Strength
Mosler MT900S	270+ / 435+	Speed Traps, Highway	Ultimate Top Speed
Koenigsegg Agera RS	265+ / 426+	Standing Mile	Incredible Acceleration
Ferrari 599XX Evo	260+ / 418+	Circuit Racing	Balanced Grip & Power
Shelby Monaco King Cobra	N/A (Extreme Accel)	Rivals Events	Unmatched Acceleration
Bugatti Veyron Super Sport	255+ / 410+	High-Speed Stability	Ease of Use

So, if your goal is to see the highest number on your speedometer, the Mosler MT900S is your best bet. Just be prepared to spend time in the upgrade and tuning menus to unlock its full potential.

[SanCarlos]

For just blasting down the highway to see a big number, grab the Mosler MT900S. It's a community favorite for a reason. You can find it in the Autoshow. Dump all the best upgrades into it to get it to X class. The trick is to get a good tune from the creative hub—search for "top speed" tunes. I've hit over 270 mph without much trouble. It's a handful to drive, but wildly fun.

[GriffinMarie]

Speed is relative. The Mosler is the top speed king, but it's not always the fastest around a track. My go-to for winning races is the Ferrari 599XX Evolution. Its acceleration and grip through corners are insane, which often leads to a quicker lap time than a pure speed machine. The Mosler feels like a rocket on a rail, but the 599XX Evo feels like it's glued to the road. For actual racing, cornering speed beats top speed every time.

[StElisa]

As someone who loves collecting and testing every car, I look at official leaderboards and community data. The consensus for highest achievable speed, backed by countless player tests, points to the Mosler MT900S. It's not just anecdotal; you can see its dominance on the in-game speed trap leaderboards. While other cars like the Agera RS are phenomenal, the Mosler's combination of lightweight construction and massive horsepower from upgrades gives it that slight edge for this specific record.

[VonJosiah]

Don't overlook the tuning! You can buy the "fastest" car, but it won't hit its max speed without the right setup. After you get the Mosler and upgrade it, the final gear ratio needs to be lengthened for higher top speed. You also need to minimize downforce in the tuning settings, which makes the car less grippy but reduces drag. It's a balance. The right tune can add 10-20 mph to your top speed. So the car is half the battle; your skill as a tuner is the other half.