For those upset about the red Ferrari not being called Mirage, this post might just be considered a pile on before it’s all said and done with news about Wheeljack. In a Shoot for the Edit thread called "Clarification", Nelson decided to clear up the confusion on who the buddy team is in the movie.
He wrote, "For some time now, I've implied through some of my post that Wheelie's sidekick was the Mercedes E550 (the E550 is a whole different character). It's not. My bad, my apologies. Brains is Wheelie's buddy. And what's Brain's alt-mode you ask? You'll have to wait and see. He later added, "I've read all the scripts in two languages. I got my two robots mixed up, plain and simple. Move on." This bit of info aligns with the comic and novel adaptations which revealed a character called "Brains" that is about the size of Wheelie.
Now this is where the aggravation comes in for some for he once again decided to muddy the naming waters he comments about the blue Mercedes, "Has Bay confirmed it's Wheeljack?" This was followed by, "Here's your problem: you keep assuming the packaging and novels are the end all, be all. People assume they dictate Bay what storyline to follow, what to name characters, etc. Until anything is officially confirm here or by Bay in the press, all bets are off."
It is important to note he didn't deny the name, simply pointed out that it has not been officially confirmed by Bay in some form or fashion. The name was verified by the leaked comic book adaptation a few weeks ago and also used in the novel. As we already learned with the Ferrari (and really back in TF 1 with Devastator/Brawl) is that what the final draft of the script says and what Bay decides by the end of post-production isn't necessarily the same thing.
As always keep in mind that the script the adaptation writers are working off it is produced more or less at the same time as production begins and getting ready for publication around the same time as post-production without them being informed of any changes that may have occured in that time. Since the Transformers are pure CGI creations, Bay has a whole lot of flexibility in changing certain details (like their name) of new characters right up to the end as all it is in most cases a is simple change in dialogue. Remove or shorten a few lines from the first two movies and we wouldn't know the names of most of the secondary Transformers characters outside of the toy packaging. Arcee's name was mentioned once, Sideways never, Brawl as subtitle text, Soundwave once, the individual robots of Devastator never, and so forth. For all the weight the names get from Transformers fans, really the secondary character names are incidental to the movie and probably most important to Hasbro for the assist they provide in toy sales.
Speaking of Hasbro, have you noticed that we really have not seen the line-up of toys regarding the Ferrari or the Mercedes? Most of the other Autobots already have either hit toy shelves or images have leaked in some form or fashion but not these two. A single matchbox car isn't proof compared to the multiple versions of the other characters that we have already seen. That tends to indicate that while Hasbro was informed too late for them to come out with the initial wave, they might have had enough time to make sure the packaging matched the movie to avoid the brand confusion that occurred with the Brawl/Devastator toys.
So the question once again becomes, what is the name of blue Mercedes-Benz E550, aka "Einstein"? Does he remain Wheeljack and if not what is it really?