-( Story related, cannot be missed )-
As Ripburger tries to drive you off the road, flip up the yellow part of the front of his truck. He'll attempt to push it back down so he can see with his cane. There's a small window of opportunity here to get his cane, so if you can't grab it at first, keep trying. After you obtain the cane, open the grate over the engine fan and use the cane to slip through, allowing you to pass through to the other side of the carriage.
Here, you'll see several fuel lines. For speed and efficiency, take out your tire iron and remove the far right-most one connected to the carriage itself. Ripburger will try to shoot at you after you've removed it but Mo will come to your rescue right as the Vultures catch up and eat the truck.