The Airfield is located in the centre of the map in Silver lake on Nelson Way
, there is one entrance which is on the right side of the road when travelling south of the map (Away from the Junkyard).
Here's a map with the entrance location
Once you are driving one of the toy cars (Id suggest the Toy P12
) head into the Airfield and use any of the split ramps to perform a barrel roll, you will need to get one half of your car on one side of the split ramp and the other on the smaller ramp to perform a full barrel roll. A run up and use of boost is suggested.
You will also unlock the following if you havnt already
Here's a video