This is anecdotal, hearsay and probably not true, but a digger driver once told me that the reason theres so many chinese diggers and other heavy equipment over here these days is that if you are a chinese company and want to buy 1 western machine, you need to buy 10 locally manufactured ones and keep them for x amount of years.
So according to this dude the chinese companies would buy like a 100 local diggers and 10 western ones, park the locally produced ones in a storage until the x amount of years have passed and then sell them to the west.
Again, this was according to just some dude who digs holes in the ground. No idea if its actually true, if anyone knows I'd be interested to hear whats the reality.
There's like a 15% tariff on imported cars (from memory), they're definitely over priced there and always have been. There's foreign brands thar aren't imported, ie produced locally. For a while GM Shanghai was making a fuck load of cars there but its slowly been tapering off. My CN Telsa was bit cheaper than the same one in the US. But I couldn't tell you that it's apples for apples, sometimes the local model of something is cheaper because it's made of cheaper stuff.
The bigger issue for big city china when buying a car is the plates. If its an ICE the cost of getting plates can be 100x that of a EV. Regardless of where it's made.
As for stuffing products in a friendly customer or by some kind of stupid regulation is not common but happens. There is a complex web of incestuous company ownership and an equally complex web of influence and indirect ownership by the government. If someone needs to hit their numbers real bad it's possible they'll ask / insist / regulate that another company buys up to help make it happen. There are a few laws that are supposed to prevent it, but if nobody complains then probably nobody investigates.
I've seen this happen a few times with stuff much cheaper than diggers.
Err, I'm pretty sure most European car makers manufacturing their Chinese models in China. A tariff would be largely meaningless. The EU officials basically told Chinese makers to do the same - bring the manufacturing here to avoid tariffs. Sounds like this might be a political move on the Chinese side as to not appear weak.