Some more info.
As I mentioned earlier, every thing should have a Type, and Types can have Features. Below is a basic listing (not finalised, but close) with Types as columns and Features as rows. An 'X' means it is a valid feature for that type. Some Features contradict each other (like you can't be both Fast and Slow) and some have prerequisites (you need Jet Engines for both Supersonic and Hypersonic) but that's described with each Feature.
Features Available
Features | Aeroplane | Airship | Grav Vehicle | Ground Vehicle | Hovercraft | Rotorcraft | Structure | Submersible | Watercraft | Walker |
Aerodyne | - | - | - | - | - | X | - | - | - | - |
AFV | - | - | X | X | - | - | X | - | X | X |
Agile | X | X | X | X | X | X | - | X | X | X |
ATV | - | - | - | X | - | - | - | - | - | - |
Biotech | X | X | - | X | X | X | X | X | X | X |
Fast | X | X | X | X | X | X | - | X | X | X |
Floats | X | - | - | - | - | X | - | - | - | - |
Folding Wings | X | - | - | - | - | X | - | - | - | - |
Hybrid | - | X | - | - | - | - | - | - | - | - |
Hydrofoil | - | - | - | - | - | - | - | - | X | - |
Hypersonic | X | - | - | - | - | - | - | - | - | - |
Jet Engines | X | - | - | - | - | - | - | - | - | - |
Locomotive | - | - | X | X | - | - | - | X | X | X |
Monowheel | - | - | - | X | - | - | - | - | - | - |
Multi-Legged | - | - | - | - | - | - | - | - | - | X |
Off-Roader | - | - | - | X | - | - | - | - | - | - |
Open Frame | X | X | X | X | X | X | X | X | X | X |
Open-Topped | X | - | X | X | X | X | X | - | X | X |
Ornithopter | - | - | - | - | - | X | - | - | - | - |
Rail rider | - | - | - | X | - | - | - | - | - | - |
Slow | X | X | X | X | X | X | - | X | X | X |
Smart Wheels | - | - | - | X | - | - | - | - | - | - |
STOL | X | - | - | - | - | - | - | - | - | - |
Streamlined | - | - | X | X | X | X | X | - | - | - |
Supersonic | X | - | - | - | - | - | - | - | - | - |
Tilt Engines | X | - | - | - | - | - | - | - | - | - |
Tracks | - | - | - | X | - | - | - | - | - | - |
Tunneller | - | - | - | X | - | - | - | - | - | - |
(before anyone asks: A streamlined structure can be the basis of a rocket stage, and rocket thrusters, nearly directly lifted from the current version, makes a really simple basis for building actual rockets: the stages above are 'cargo' for multi-stage. Just as a test, the builds emulate a V2 pretty closely at TL5 and you can sneak a SSTO rocket in at TL8 (barely), so I think it's ballpark and all you have to do is count the number of rounds you have for rocket thrust - there's already rules for how you move up the speed bands, and I just expanded it for passing from Hypersonic to Orbital (based on world Size). And I then lifted Heat Shielding from High Guard, because you need to be able to slow down, either by thrust or by friction, if you want to re-enter.
(Grav vehicles don't need to worry as much, since they can float above the atmosphere at much slower velocity and even if moving fast, can slow down to safe speed above the atmosphere before re-entering at fairly slow Speed - it's a whole different paradigm than rocketry)
Streamlined doesn't apply to aeroplanes, because Supersonic and Hypersonic already cover that sort of effect and are costed well enough to take into account shape, materials, and engine changes needed to push the envelope.
An AFV Structure is a bunker...
Also, not on this are power choices as I mentioned and other auxiliary drives, including Lifters, which follow the T5 definition of being good for Very Slow movement at best (but you can tow them if you really want to try making a grav train).
And that's enough for now. Gotta write some stuff...