Reliance on non-repairable electronics everywhere, fully sealed mechanical parts, etc. Efficiency comes at the cost of more moving parts, more sensors, higher pressure, tighter tolerances, which all introduces more failure points harder to debug/replace. Not to mention lighter thinner non-cost prohibitive materials are easier to damage.

As a rule of thumb, I will only buy pre-2008 vehicles, things only went from bad to worst after that era.