They seem mute when they're in their vehicles/alt modes. Maybe because their mouths go somewhere else when they're transforming? Optimus says "Calling all Autobots", but that seems more like a recorded message.

Can someone please correct the title? cause I was in a rush and I misspelled Transformers

 

The Decepticons talked in Cybertronian while in vehicle mode

 

I meant in English. Oh, and the twins and Arcee actually talked in English while in alt modes

 

Optimus spoke on the radio and Bumblebee spoke to almost all of the human protagonists at least once in vehicle mode.

 

A better question is how do they see in alt mode?

 

They was transmitting signal (messaging) in their alphabet, i don't think there is such thing called Cybertronian language in this movie. Cybertronnian actually speak English

 

No,they were talking,almost everyone talked in Cybertronian:Frenzy,Starscream,Megatron,Shockwave,Rampage,Brawl,Barricade,the Protoforms and even Prime in AOE(but his Cybertronian seems more like talking than the others)

 

No there is Cybertronian because in the first film they talked about learning Earth's languages from the internet. The sound we hear when the Decepticons are reporting in for the battle at Mission City seems to be what the language sounds like to humans.

Also in Revenge of the Fallen we find out that their language has evolved over time because the Twins can't read an ancient version of the language that was no longer in use.

I think the reason they don't use their native language much in the films is because it is a visuals heavy series of films and people would find it distracting trying to read the subtitles and take in all the visual aspects of the action at the same time.

 

The Twins and Wheelie couldn't read the language because it was the language of the Primes.

 

Jetfire spoke in vehicle mode; we hear him shout "Incoming!" before he transforms in Egypt.

So, they can. It's just, they don't. Which kind of sucks.

 

I don't think i have even heard any of them speaking cybertronnian, I only see Transformers letter, which is indeed not English Alphabet. Isn't it weird to you when The Fallen speak English while he's on the nemessis and when he was in the past 10,000 BC? While English is not their language like you said.
I think when Optimus said:"We learned Earth language through the WWW" he means they learned how to talked like a street punk (jazz) or like a samurai (drift)

 

That the sound they make when they transmit signal, some of the word Rampage and Barricade said might sound like cybertronnian to you because the voice processing make it kinda hard to understand. I have no idea what Prime was speaking in AOE but i think it's highly likely that he was speaking accient language of the knight

 

OP said "The legend is true"or something like that

 

I haven't seen the older movies in a while, but to me it sure sounded like a Cybertronian language. It seemed that was the intent of those scenes, and I loved that...please don't take that way from me...LOL

 

i assume they can, but after someone told them about talking cars in that PIXAR film, their Bay-ish nature said, "we're not copying that...we'll just be quiet."

 

Characters suddenly and conveniently speaking [Your Language] is a really common film/TV contrivance, it's just so the audience doesn't have to read captions any time they're on screen. A classic example, the German bad guys in WW2 movies aren't suddenly literally speaking English when the English characters aren't around, it's so you can understand them without the need for captions, that's exactly what's happening in that scene in ROTF on the Nemesis, only English instead of Cybertronian. Are you really not familiar with that sort of thing in movies?

Anyways, while it's happened on a couple of occasions I don't know why speaking in vehicle mode isn't utilised more in these movies, it's a definite waste of opportunity for getting to know characters, both human and robot, and just getting exposition out of the way, instead of wasting time with "ok we've driven for a bit with no real expansion on what's happening, now we can stop everything and talk for a bit".

 

They really should talk in vehicle mode more often. I voice over would be a cheap way of character development during a driving scene.

 

It would be awesome if they talked during vehicle form. Most of the Transformers series had them talk while in vehicle form.

 

Could have given Sideswipe and Dino more dialogue in the DoTM highway chase scene.