Binga,

Ok so I'm gonna talk through my thoughts and changes in the deck. First of all, (almost) all changes will be cards that are under a dollar, most being 50 cents. My goal isn't to make you spend a bunch of money, mostly just take out cards that don't gel well with the commander.

When I build a commander deck, I always break down the commander's elements and choose what direction seems the smartest and/or the most fun. For the Gold King, I see: human type, wants to tap/untap, exiles creatures when he untaps, makes artifacts that can be used as mana. So: he helps with creature removal so we can ease up on creature removal cards a bit + he makes artifacts that tap for mana, so we can comfortably put in some more expensive to cast cards a bit more comfortably. Cool, we can keep that in mind.

The main direction I want to take this deck in is the in regards to the fact that he makes Gold. That's his most unique feature, the rest is gravy. I see your build has a lot of Human payoffs but I think it takes more work for less payoff to go down that road. I'm not completely removing the Human element since Macar is a human and we will always have access to him since he's the commander - but the Human thing is mostly going to take a backseat. If we can tap/untap the Gold King A LOT then we can wipe your opponents creatures and make a bunch of Gold. Since we're gonna do that, makes sense for us to play a bunch of cards that reward us for playing lots of artifacts or having lots of artifacts on the battlefield.

I didn't understand before why this was a Vehicle deck but now that I'm looking into this build, I see that they are being used as an easy way to tap Macar. I also want to add a little bit of Haste enabling into this deck so Macar can attack the turn he enters the battlefield and we can add some cards that make him unblockable so that he can safety tap and attack without worrying about someone blocking and killing him. The thing to keep in mind with crewing Vehicles is that you cannot tap Macar to Crew a Vehicle unless the full Crew cost is paid. Like, if it says Crew 4, we aren't doing the dang thing unless can assemble 4 power between X creatures. So, I'm going to add some creature token generation into this deck to make sure you're always crewing your vehicles pretty easily. 

This deck doesn't have enough Vehicles, baby! We're adding more!!

This deck's (new) strategy is tap/untap Macar as much as possible to make as many Gold tokens as we can. We can use these tokens as mana, like they are intended, or we can sacrifice them (along with other artifact tokens in the deck) for different bonuses like card draw, giving other creatures -1/-1, etc. Because Macar is only one guy who makes Gold, we also have other cards that will be making Treasure, or Food, Servo or Blood tokens. These are all artifacts and the more little artifacts this deck has on the field, the stronger it will be. Servos are also creatures and therefore can help crew the Vehicles. Basically, I've found cards that do two things at once (i.e. draw a card and make a blood token, destroy target creature and create a food token). These added benefits make the cards a bit more to cast but having most cards in the deck play into the main strategy will be helpful.

Cards i included that are above 0.99 cents (they were way too good in your deck to leave out):

-Mukotai Soulripper 1.99

-Kuldotha Forgemaster 1.99 

Cards that are very nice in this deck if you wanna spend some cash:

-Honor-Worn Shaku 4.99

-Mechtitan Core 1.99

-Surgehacker Mech 1.99

-Inspiring Statuary 5.99

-Herald of Anguish 2.99

-Academy Manufactor 4.99

-Fain, the Broker 2.99

-Tempting Contract 2.99

-Puppet Strings 2.99

-Smuggler's Copter 4.992