Seems I remembered it the wrong way round – it was the Corsa that held up and crumpled well enough to not have significant intrusion even at 110 km/h (70 mph).
This isn't really evidence that it's possible to make an engine that can crumple. In fact, quite the opposite.
This particular Corsa B (93-2000) was a 1.4i (1.4L engine) - the physical dimensions of the engine are extremely small[1], and there is a lot of empty space in the engine bay that isn't taken up by the main engine block (excluding various plastics, wiring, etc - actual metal). I don't think it's so much the case that this engine "could crumple", rather that there was a lot of space for the front to crumple into, before there was none left and the engine was then pushed into the cabin.
Engine blocks are, well, blocks of metal. They're not going to crumple in any meaningful way.
