For this achievement you need to brake from 64mph/100kph in 2 seconds or less.
The best car to use for this is the
Formula A on a track with a good straight, something like
Road America or Nurburgring.
From the main menu enter 'Solo' and create a race with the above settings then once the race starts get the car up to 64mph/100kph and then hold the
down fully until you stop.
Here's a video