You'll probably get this through natural progression through the game, but if you can't wait to get this, simply drive around on the highways, and you'll get this after about an hour. I'd reccomend using the Lamborghini or the Buggy, as both vehicles are extremely fast, and this will come much faster.
Edit: Forgot to mention this is cumulative (Special thanks to B0ngAAA and I2 INCH TONGUE for reminding me)