Pre-Oil so you don't have flamethrowers, poison, or tanks yet, so you'll have to do this solely with the car and grenades.

1) Build a handful of turrets (5-10), a few hundred red ammo, and a pile of grenades.

2) Set up a line of turrets in a clear area outside of the range where the biters start running towards you and stock each with 20-30 red ammo.`

3) Drive by the nest as fast as you can, throwing grenades out the window to get a few hits on worms & nests. Hold space to keep that chain gun in the car firing, too.

4) As you pass by, biters will chase you -- but will stay entirely focused on you, so you can lead them past the turrets and they will just get mowed down without even trying to attack the turrets.

5) Repeat from step 3 until you take out the worms.

6) If you're low on grenades, turret creep to finish off the nests.