I know this is gonna sound like weird advice but the real key, in my opinion, to drawing tech/vehicles isn't the base shapes. It's all in the transitions between those shapes. The smooth seems between doors and frames of a luxury vehicle...the janky plates and pipes of steampunk...the exposed wires and energy sources of a mad scientist.
I'm of the opinion, because of this observation, that unlike figure drawing or storytelling thumbnails...
You gotta do full renders of tech/vehicles to get better and better at it.
My two cents.