The SC defined arrest as this, in Terry v. Ohio:Maybe arrested for purposes of Miranda ... But, certainly not for all purposes. While the force used was equivalent to an arrest, a release at that point would not have required documentation pursuant to PC 849(b) as to the police this was essentially a secure detention.
...It is quite plain that the Fourth Amendment governs "seizures" of the person which do not eventuate in a trip to the stationhouse and prosecution for crime -- "arrests" in traditional terminology....
Mendenhall lists one way of a person can believe they are "Seized" is that there are multiple officers present. An arrest they said before is the "quintessential "seizure of the person" under Fourth Amendment jurisprudence."
Some case law from the 6th circuit indicates when a person is placed in the back of a police car it is an arrest, (emphasis added), but so is an UNjustified prolonged Terry Stop.
I posted it over on expertlaw, but I am at the library right now and do not have my notes with me.
Of course we both know that type of arrest, if we want to call it that, is not a right to search a person "incident to arrest".