The U-2 is regarded by many as one of the most difficult aircraft to land and maneuver. By having another U-2 pilot on the ground after a long mission, it's reassuring for the pilot in the cockpit to know that a fellow aviator has got his back.
For decades, the chase car driver has provided the pilot with an extra set of eyes and ears on the ground as he or she talks the pilot down from a high-altitude sortie.
In this image, a 1968 SS-396 El Camino screams in behind an early U-2R model descending the last 5 feet before touching down on the tarmac.