The other part is, that producing cleaner Diesel cars is just more costly -- that was the main reason for VW to cheat.
Obviously, it would soot orders of magnitude more - but I wouldn't be surprised if the NOx emissions were surprisingly low, seeing as efficiency was way down on Toyota's list of requirements; they just made a bigger fuel tank.
It was designed to just work(tm) - almost regardless of what happened to it. Gas mileage? Not as much.
However it does consume more AdBlue and/or produces less power the cleaner it is
They did it to sell a "better car" with disregard to pollution regulation
This is why it's more costly. In order to design a diesel car that meets the exact same specifications, they either need to add an entire urea system (costs more money to manufacture, plus ongoing AdBlue costs to the consumer) or add a larger less efficient engine to meet the same performance target (costs more money to manufacture, plus ongoing higher petrol costs to the consumer).
Making a non-polluting diesel car is certainly more costly than making an equivalent diesel car that you don't care about pollution on at all. You're adding a big engineering constraint, of course it gets more costly!
I should add that I'm all in favor of cutting down pollution, and that if diesel as a technology turns out to not be that practical anymore for small cars, then so be it. Eventually they should all be zero emissions anyway.
This is tricky because, in the US market at least, one of the major appeals of small diesel cars was their performance / low end torque. There aren't really any other options on the market right now that can offer the same mix of performance/efficiency. Diesel cars are definitely on their way out in the US but I'm not sure it will be a net gain in the end. Lots of people such as myself are choosing to replace their small diesel cars with bigger, less efficient, similar performing cars.
Friend of mine is ditching his VW Diesel TDI for a Chevy Bolt at the end of the month. I'll be interested to see what he makes of that switch. Electric has if nothing but low end torque.