I have uploaded an AWD S1 tune called What's "Safety"?
for the 1975 Lancia Stratos, Creator: B0BCAT (0 is a zero) to help with this achievement.
Once you have upgraded your car, play through the Blizzard Mountain DLC until you earn 60 stars which will unlock the Hot Springs Danger Sign
on the upper right of the map.
Your starting point for the jump is behind the Hot Springs Bucket List Blueprint. Reverse up the snowy bank near a small rock for an extra run up. Try to reach 100mph+ as you hit the jump and aim slightly right off the ramp as you take off.
It has been requested that I include the jump distance in metres for those using metric settings. A quick Google search reveals that 825ft is 251.46 metres.
Thanks to AussieBigfoot
for noting that it takes 60 stars to unlock this Danger Sign in the single player career.
It has been mentioned in the comments that this Danger Sign can be attempted at any time in Online Freeroam (thanks to FullNietzsche
for the heads-up).