Cars ain't remotely the same as the subprime crash, though it won't be pretty.
When you can't make the payments on a PCP or lease any more, the car - the asset - returns to the finance company, who in many but by no means all instances is the manufacturer. Better for them in some ways, but not others, that it's someone else, a bank. It continues to exist as a commodity but if this happens en masse then the oversupply devalues both used cars and, by opportunity, puts a brake on selling new ones. Not only that, but as well as the general appetite to either offer or take finance reducing, the GFV of finance arrangements declines too and so the financing requirement for a purchase increases. All in all, not just a financial hit, but also very hard to sell cars at a profit. If the manufacturer can't ride that pattern out - or indeed manipulate it by, say, destroying its returned cars - they'll go bust. There ends the tale.
There will be some outstanding personal consumer debt involved here - the negative equity on early termination - but it's strictly finite and comparatively small compared to mortgages. Most consumers won't lose their shirts.
Aside from the scale, unlike housing, there's no speculative or leveraged element to it, the assets are transferable commodities, a default isn't so simple, finance terms are fixed for the duration of the loan, the owner of the debt is probably generally better contained, the societal outcome isn't as disruptive, etc etc.
But if it does fail en masse, it will put a big dent in confidence, on which the economy depends, and therefore could be a trigger for other bigger failures.
