Forza Horizon 4

Car: Mercedes Benz #24 TANKPOOL24 Racing Truck
Tune: "Danger Sign" by "Maka91"
Danger Sign: Ambleside Edge (Left of the Hub)

If the danger sign is not available to you, make progress on the danger signs you have to unlock more.

Approach the danger sign from the south, using the dirt road, and a straight approach to hit the ramp at your highest speed. You should easily go over the required distance upon landing and the achievement will unlock.

As an alternative to the first solution, you can purchase the cheaper Mercedes Benz Unimog U5023 and equip my tune, called 'Ground Force'. Use the same danger sign, Ambleside Edge and you should hit the 3 star target straight away.

A much cheaper alternative using the Unimog, I did this for about 85,000 Credits.

I bought a Unimog off the Auction house for 55,000CR buy it now (trust me they do appear quite regularly at that price). If you're not too bothered just buy one for less than 100k, if its been tuned already then its a bonus.

With tuning I only upgraded it to Max class C 600 which only costs around 30k compared to the 400,000k plus using S1. The tune i used was called Cheap Power under the suggested tunes tab.

You can also upgrade it to class B quite cheaply. Just search for class B tunes, there are lots. It's probably a lot easier this way but its definitely possible at class C.

I used the Ambleside Danger zone for this too, you need to get to about 120 MPH which is fairly easy to do if you go back far enough. It'll take a few attempts, just use the rewind tool to get the best angle.

Straight after I sold my Unimog on the auction house making a bit of profit.

Note: This is much more difficult in winter, I recommend either waiting for another season or upgrading the unimog to a higher class (S1) if you don't mind spending A LOT more credits. At the time I was saving for the castle so I couldn't afford it.

Volvo Iron Knight

setup: flying knight

Ambleside Edge

start in the small forest south of the sign at the small intersection. accelerate carefully through the corner and as soon as the road is going straight you go full speed.

252 meters at the 1st try. easy

CHEAPEST METHOD (127.250Cr max)

all you need is:
1) a truck called "UNIMOG U5023" of the brand "MERCEDES-BENZ", which costs 100.000Cr (you can find for a lower price in the auction house)

2) download and install a tuning called "GRND FORCE(CHEAP" (to find the tuning just go to "garage">"upgrades & tuning" > "find new tunes"> "search" and search for the tuning name in the "description") this tuning costs 27.250Cr and will change the class of your vehicle to [B 646], enough to perform the jump

after doing this, you simply need to make a jump at 200Km/h (124 mph) in the danger sign "ambleside edge", near to Horizon Festival (do the same as shown in the video), it will be enough to get the 3 stars and unlock the achievements.

Easily Beat this achievement in any of the trucks!

Trucks:
A) 2014 Mercedes Benz UNIMOG U5023
B) 2015 Mercedes Benz #24 TANKPOOL24 Racing Truck
C) 2015 Volvo IRON KNIGHT

Tune:
A) "Cheap 3 Stars" by "Demon Fox 00117" - Although mines probably more expensive than required
B) NA
C) NA

Danger Sign: Ambleside Edge (Left of the Festival site)