DiRT 2

To get this achievement, start a Free Race Trailblazer in Utah at Hurrah Pass and ensure in Race Setup that Damage is set to FULL. Choose a quick car (easiest is probably the Evo IX - Thanks Spilner1001, but have confirmed it will work with the Evo X, Solstice GXP and BMW Z4 M).

From the starting line, floor it. You'll pass over a ridge, and start coming down a hill to the left and will get up to above 225km/h (140mph). At the bottom of the hill, just run into a tree/rock/etc and Achievement Unlocked.

If you're still having difficulty, you can change your car's setup to favour top speed instead of acceleration - thanks sharndowg.

Before you can unlock this achievement you will firstly need to have unlocked the All-Star class and an event that contains the Hurrah Pass in Utah.

In the Dirt Tour map select Utah and 'Free Race' bottom left, and select Hurrah Pass as your track.
Accept this and you can select your difficulty settings, you will want the following:
Damage - FULL
Vehicle Setup - ON

There are a few cars that work:
BMW Z4M Coupe Motorsport
Pontiac Solstice GXP
Mitsubishi Lancer Evolution X
Dallenbach Special
Mitsubishi Lancer Evolution IX - This is the car i used.

Before the race starts set your gear ratio one step longer.

When the race begins accelerate fully and you will come to the crest of a small hill decline, follow down till you get near the bottom where the road turns to the right, there will be some trees and rocks in front of you, drive straight into them for your achievement.

I hit 150mph at the base of the hill (As seen in my video)

Here's a video demonstration (Note i had already unlocked the achievement.)