You can use a lot of the names already given, but I would connect each manufacturer to a type of brand-naming.
For your standard parts and things. Has some more run-of-the-mill names that have some resemblence in the name. Similar to Samsung using the Galaxy, Apple using the Iphone (or Ianything) etc. The names would be pretty safe and not incredibly indicative of anything.
Sets the standard for the industry by building average vehicles for each tier, could easily be the starting tiers for each player. To please the buyers they are easily modified with parts from different companies.
Known for their no-nonsense heavy vehicles, it builds only heaviest two tiers and will be known for producing the heaviest of the heaviest even among those. The vehicles themselves are much less customizable than those of Omni-Dynamics and are specialised in their roles, but Bantam industrial will build parts to customize other vehicles.
Looks would be blocky, brutal outwards visuals with as much noise, thrusters and bombastic display as you can get.
Names would be on the lines of the already proposed things like Mammoth, Ragnarock, Kraken etc.
Tachyon is a theoretical partical that goes faster than light, so guess what kind of vehicles this company will be making. It builds various tiers but has the most small-tier vehicles available. It specialises in high-speed and control while on the road, and doesn't bother much with things like "armour" and "firepower" and assumes you'll either outrun the things that get fired or recover so fast that you'll be overtaking your enemies before they can grab their next weapon.
Looks of the vehicles is small, sleek and purposeful. Names are things like the proposed cheetah, veliciraptor, leopard etc.
Just as a baseline idea for companies, a general type, a specialised heavy type and a specialised high-speed type. You can add a few extra manufacturers that are even more niche or combine strange traits, these manufacturers can be the one's trying to go toe-to-toe with the established main manufacturers.