> Make foreign cars expensive and there will be substitution with local cars.
This is quite true, but the problem is those cars will be a lot more expensive. That means a small number of people employed making the cars benefit, while the vastly larger number of people buying them lose out in higher costs. This never works out to the benefit of the country as a whole and low wage earners are the ones that lose out the most. For every car those workers make, they buy dozens of other goods which, if more expensive due to trade barriers, more than soak up any increased wages they might have.
Actually it's worse than that, because often many of those workers could have been gainfully employed is other industries. Only a small minority of our theoretical car workers would actually have been unemployed in a globalized world.
It's the same with Brexit. The vote was driven by working class people on low incomes, but the impact of inflation from the fall of the pound and further economic problems when we do actually leave the EU will predominantly fall on them. Middle class people like me have enough marginal income to absorb the hit. People on low income don't.