. I’d have thought it’s not so much blown engines which scrap cars these days, it‘s electronic faults.
Very few blown engines. I've killed a few:
1992 Cav 2L, actually both I and a mate failed to kill this in over 200k miles. It just turned into a rat with a pile of faults, no one of which was terminal but on a car with 200k miles in 12 years not worth fixing.
1992 Alfa 33, blown engine at 10 years/80k miles (!) An independent garage bought it, fitted another engine, the gearbox failed a month later.
1993 Volvo 440, turned into a rat at 14 years/120k miles, taken to a scrapyard in France when I returned to live in the UK.
1999 Peugeot 406, stolen and recovered at 10 years, 120k miles. BER.
1993 Astra, sold as a runner at 19 years/110k, failed next MoT, BER. Still (just) viable but used cars were cheap back then, and as Tony says a 20 year old Astra is OK when it's costing you nothing and you just drive it about locally, but that's all.
2003 Vectra, turned into a rat at 10 years/120k miles, sold cheap and failed next MoT.
1999 Saab, still running at 90k/14 years when I traded it for:
2003 The Indestructible Mondeo, which did 60k trouble free miles in 4 years, sold as a ratty going concern at 160k miles/12 years.
1999 Mazda MX5, failed MoT, corrosion, at 19 years/100k, and by then sufficiently worn to be no fun to drive.
2007 Jaguar 2L diesel, gearbox bearings failed at 12 years/120k miles and BER. Sold for scrap/repairs
2007 Jaguar 3L diesel auto, corrosion at 200k miles/13 years. Still mechanically sound, sold cheap. These engines fit Land Rovers and are sought after.
2009 Audi A5 3L diesel, still very sound at 14 years/200k miles. Running repairs have been needed, obviously, but no major repairs.
So if there's a theme, it is that after 12-15 years the things get generally ratty and no lonjger worth repairing.