Here's another U-2 link - a story about landing after a flameout
Above & Beyond: I Have a Flameout | Military Aviation | Air & Space Magazine#
About the the chase car, the article says:
"Because control at low speed was marginal and landing required a full stall, all landings were assisted by another U-2 pilot driving a Chevrolet El Camino with a souped-up engine. The driver raced down the runway behind the landing airplane, radioing height information: “One foot…six inches…hold it off…. Good touchdown!”