Quote: Recently a taxiing Lufthansa crew reported a TCAS target at the position of the follow-me car in Hamburg. They asked if the car was equipped with XPDR. The tower controller even checked via phone but then reported it was not.
Some airports use a new Airfield Surface Movement Indicator system that uses Mode S rather than primary radar. Some vehicles at these airports have a special Mode S transponder fitted to keep the system updated. So the answer could be yes.
Ghost returns are common from some missile systems. Pilots flying up the East coast of China may be familiar with a TCAS diamond with no height readout just to the East if Xiamen. This is a Patriot missile battery which Taiwan has positioned on Kinmen Island. The Patriot system has an IFF interrogater which some systems display as a No Mode Charlie TCAS contact, whic is why the Chinese won't let you do a weather deviation to the East on thay airway.