Okay, what batt are you using? Some can be quilted 8/10 inches apart. With any quilt you machine quilt, it is best to start in the middle and quilt out so that any extra fabric moves to the edge.
If time is of the essence, baste your sandwich (already done?)and starting from the middle, use your walking foot to quilt in the ditch across the width of the quilt between the appliqué and pieced blocks. Once the quilt is stabilized, you can come back in and quilt around the inner squares in the pieced sections and outline quilt the vehicles in the appliqué sections. If the batt says quilt as far away as 8 inches than that can be enough quilting. You can add other quilting details if you still have time.