Bay's claim to no mass displacement was immediately debunked by the Cube scene in the first movie. But let's assume mass displacement didn't exist. Looking at each Cybertronian and their alt modes, can you say that anyone of them would have space in their vehicle modes for humans especially after the introduction of stealth modes? I can only see Starscream and Jetfire because the space for room is on top of and in a small area of their bodies. Perhaps Ironhide and maybe a couple of those random construction bots.
As far as I know: Maybe Brawl Maybe SP Maybe OP Maybe Leadfoot That's all that I got at the top of my head.
I stopped caring about vehicle-robot scale a long time ago. I just automatically asumme there is some type of size changing involved. Anyone who wants to photoshop the Portal Space Core into a Transformer's vehicle interior would a hero.
I don't think there was any mass shifting. I just think it was a lot of folding, as can be seen in the transformations on screen. Even the cube didn't morph slowly, it did a lot of folding down.
1. The cube managed to compress itself down into a really small part of itself, yes, but it's a cube that created a race of transforming robot aliens and had other, nonspecifed powers. Being able to compress itself doesn't seem that hard, not when things in real life can do the same thing on a much less grandiose scale. 2. If I recall correctly, only Bumblebee is seen using his "Stealth mode" at one point, and even then Sam is still riding inside him. Optimus Prime, Ironhide, and even Soundwave have had humans inside them as well and they seem to have enough space. 3. F-22's and SR-71's are HUGE and have relatively small cockpits in relation to their overall size. Plus Starscream's cockpit needed to stay intact to please the G1 look wanting crowds.
Who's to say how much empty space there is in the robot modes? Maybe they are all just big metal balloons.
Never mind that they're alien robots from a planet made entirely out of metal who can transform into any chosen vehicle and speak English.