Yes.Live data is obviously logged with car running.
At the dealers they "Diag" the car at idle and occasionally rev it (depending on what they are testing) but because the car is not under load,a remapped car will not register parameter values much different from a standard car!
This is why "tuners" say it wont be noticeable,if your car is mapped!
Its a bit of a joke ,one comment you quoted a tuner saying that the dealer doesnt have sophisticated equipment to be able to check if your car is mapped!You can get a £30.00 tool from Ebay that will read/write your Ecu


Omodos,what model and year car do have?