[RJasonKlein]

I have a 2013 FR-S and from my observations, the early models seemed to be more fragile. My understating is that there were minor and ongoing improvements made each year to address items that were identified as failure prone (especially to the valvetrain), but nothing that changed the basic specification of the engine. That said, just like in the BMW world, I'd rather have later generation engine simply to get the advantage of cumulative improvement over the years. The 2017 engines have received the biggest updates yet, but I still consider them to be minor improvements (more rigid block, new intake, polished valve guides, low-friction camshafts, updated software with far-improved TC and VSC, and other small parts). This time the horsepower got a tiny bump, but the core components and basic specifications (bore and stroke, for instance) stayed the same. Will it be more reliable? Probably, but in my opinion it's more due to continued ongoing improvements than to any major revolution in engine design. The bottom line for me is that if my budget allowed it I'd buy a newer car over an older one, but there's a lot of value in the early cars at this point.

Note: In the interest of full disclosure, this post was edited in light of additional information posted by other members below - it just goes to show you that this forum is a wealth of knowledge and that there's always someone that knows more than you do (well, than I do!) here!