Correct me if I'm wrong, but Transformers are able to pick what they want to transform into, right? Soooo what would Optimus Prime look like if he didn't pick a truck to transform into? They have to look like something before they pick what they want to be... right? what does that look like?

 

Not explicitly. They could still choose to retain their Cybertronian forms, like movie-verse and TFP Megatron, however an Earth form is better suited for the whole "Robots in Disguise" thing.

Now on to the main topic, which is a non-truck Optimus. Most versions of OP turn into various flavours of transport truck, though RID Prime was a firetruck, and all of them have been land-based by default. With that in mind, I'd say either SWAT van or some military-type transport, similar to Animated Ultra Magnus' alt-mode. Though I would like to see what Optimus Prime would look like as a fighter jet of some sort.

 

I can just see the autobots taking orders from wheelie prime....LMFAO.

 

Since this all depends on the writers writing this particular story an all...

I'll say Optimus Prime's Alt. Mode should be:

 

Fighter Jet Prime? Interesting.

But if he's not a truck, I'd say a Firetruck or a military vehicle. Never a normal car though, he needs to be something a bit bigger.

 

He was H.I.S.S. Tank in GI Joe/Cobra   and was supposed to be a Rolling Thunder Mobile Missile Transport in one of Don Figueroa's initial designs for a cancelled series.

 

I too would be intrigued to see Optimus as some kind of jetty thing, or at least something flighty. Maybe a rescue helicopter?

Also, HOLY FUCK GAUGE0001 COULD YOU HAVE USED A BIGGER IMAGE. Yeah, that's all I have to say.

 

A white lion. ^^ What? For organic mode, LioConvoy has a pretty good beast mode. But i would rather to be more IDW than BWII. the IDW looks more mechanical and with guns?  

 

Optimus Prime should always be a fire truck like DOTM Sentinel Prime, except it's more fitting for Optimus as he's heroic.

 

Optimus Prime (1995) - Autobot Leader - www.tfu.info

 

He turn into something like this


Into this


EDIT: Or a zamboni.

 

A tractor.

 

A double decker tour bus, perhaps? XD

 

Looks awesome!

Did the G1 comics ever show his cybertronian alt mode?

 

Yes, the very first issue IIRC, but it's not much to look at. Kind of like a moon rover with an artillery cannon or maybe generations straxus?

 

Optimus Prime (Protoform) - Movie Main Line - TFW2005

 

The image I posted is a concept bus.  

 

Air Force One...

 

in 1 origin he was a data clerk in another, he was working on a loading dock ... so ... perhaps a science truck thingy like (RTS)perceptor?

 

A fighter jet? Wouldn't he just be Go-Bot Leader-1?