I think you now have to pay for education if you come from outside the EU, at least in France. It is still cheaper than the US because it is massively subsidized by the working class. A person coming to EU only for free /cheap education is not welcomed.
It could change but, so far, most universities haven't applied that rule (even though they could). Even then, we'd be talking 2800 to 3800€ per year, a far cry from $20k.
I wouldn't recommend France, though, because engineering is mainly not taught in universities but in so-called Grandes Ecoles (they're engineering schools), which span years 3-5 and are only accessed after competitive exams at the end of year 2, from a sort of boarding high-school++ program (Classes Préparatoires).
For theoretical studies or even applied fundamental disciplines (like applied math), it's a different story, universities are excellent and they're easy to access (I mean, the better ones are selective, but you could get on board at any time using other degrees, unlike Grandes Ecoles) and get an internationally recognized degree from.
EDIT: Hadn't noticed OP is from the EU, in that case they would pay the same as French people, that's around 500€ per year max.