That article says the opposite you're trying to say (it clearly says Ford uses physically different engines for different variations, just that the volume is no longer the comparable or even advertised metric). That engine volume, size (and other like metrics) no longer correlates with power has been a thing since the 1950s ( https://en.wikipedia.org/wiki/Tax_horsepower ). Which is why since then the tax is not computed by size alone.

It doesn't say about manufacturers using the same physical engine, and/or having software interlocks for engine power, which would imply that on paper (and on registration) you have an engine paid for X power that can only do Y (with Y < X). People would riot if they noticed such things, as like on what is claimed on TFA.

I got downsizing mixed up, you're right. We're talking about something I didn't look up for a while now, so in mind the downsizing was connected to the ability to resize the engine with software. While the downsizing was done for different reasons, the engine configuration can and is often provided through software.

> One of the best-selling examples of ‘downsizing’ is Ford’s 1.0-litre EcoBoost petrol engine, which is available with outputs of 99bhp, 123bhp and 138bhp, meaning it effectively replaces 1.4, 1.6 and even some 1.8-litre engines from the past.

> Other advances include the way the fuel is introduced into the engine, with powerful computers and software controlling fuel injection to the millisecond and allowing the engine to shut down in traffic where stop and start is fitted.

They understood that with SW you can provide multiple configurations for the same engine. This I know for sure it's the case of Ford Ecoboost 1.0.