The Chinese spent more money on an absolute basis, yes. They gave less per car, but built > 10x as many cars, so your number of 3-5x sounds about right.
The best source IMO is the commission that came up with the European countervailing duty of 17%.
I think that it is reasonable for the magnitude of Chinese subsidies to be cheaper per-car. Even ignoring any arguments about purchasing power and government aid, I would expect China to spend less per-car simply because the foundational technical problems in building a good consumer EV had already been addressed by the time they got started.
I'm not trying to attack the impressiveness of the Chinese EV industry, because it's going to be an important part of the future. But saying that Chinese EVs are banned in the US purely because they are too good is incomplete. A big part of why they are banned, and why the US and China have such a frosty relationship, is because Chinese trade tactics are not fair to non-state-backed competitors.
Chinese EV development started in 2001. They started from a clean sheet.
Your point about fairness is interesting because that's a position the US has given up on, especially since 2025. The European EV tariffs of 17/34 percent are fair-ish. The 100% American tariffs never were
The best source IMO is the commission that came up with the European countervailing duty of 17%.