@Kingshark @Powderfinger I’m not so sure that that’s true actually (we don’t know)
@freelittlebirds as @bobthevulcan says, given exactly identical construction then both cars are equally capable of the same laptimes.
Generally there are a few fanatics who thrive on the technical side of F1, and scour every close up pic around to see whether or not the two cars have flaps in the same position or whether they’re off even just in position (I’m exaggerating, but hey…) I myself am one of them, and to be honest we probably get a good idea of whether or not the cars are of equal spec. Basically what we do is what Scarbs does – just that he writes about it, and quite a few others don’t. But he’s certainly not the only guy who scours over photos.
It gets tricky with internal piping and stuff such as the DDRS, because obviously you can see whether or not all the holes are all in the right places, but you can’t see if the pipes are really in there.
As @keithcollantine says, some drivers will tell you whether or not they have a new part, like Lewis with his Belgian Rear Wing.
Sometimes it’s the driver choice though, so not favoritism. Mind you, this doesn’t always get published, which clouds the story somewhat.