Inline six is a good configuration. Since it is a pair of threes end to end, it has perfect primary and secondary balance. V-sixes don't have that and usually need a balance shaft, more complexity, more to go wrong. While a V-8 has a wonderful sound when you prod it, a straight six is a much more civilized engine.
Problem with the straight six is that it is LONG. That's OK for front-to-back mounting, using it sideways in a FWD package is difficult, it is then awkwardly wide, which is why you see fours and V-6's in FWD vehicles.
Mercedes and Audi used a straight five for a while. The MB was a diesel and was reputed to be unkillable, the cars rusted away long before the engine died. Audi used their 2.3 liter straight five in the 80s vintage 5000 series, some of them were turbocharged and AWD, and I think VW still uses it (now 2.5 liters) in some of their vans. Some models of the Audi TT use or used the same 2.5 liter engine with turbocharging, and that makes them most interesting - lots of power, and a very distinctive sound. I had a couple of non-turbo 5000's, nice car, not very fast but lovely to drive. The turbo models were significantly faster and more complex, and Audi has never been noted for doing things simply. The crank throws in a straight five are at 72 degree intervals (72 times five is 360.)
(Incidentally, the Audi 5000 is still being made in China, and is used for government functions, limos, parades, etc. They also make a four cylinder version which is much more basic. I do have the parts catalog, but I don't read Chinese.)
Advantage of the five is that it can be advertised as "more than a four!" and engineering likes it because it is shorter than a six. GM has a five in some pickup trucks, too (Colorado?).
BMW motorcycles used Nickasil cylinder coatings in the 70's and up air cooled twins. The early models had the same problems as discussed, the coating peeled off and failed. That was fixed in later models (I don't know what they changed, but it works now).
That Stellantis engine is interesting, but man, there is sure a lot of plumbing and wiring on it! (I know there's an engine down in there someplace, we just have to keep taking parts off until we find it.) I think the biggest problem with them is given their complexity, Chrysler products' usual appalling depreciation and the rapid advances in EV technology (and dropping costs), in five years those hyper complex engines and the vehicles they are in are going to be uneconomical to repair. I'm seeing five year old Chargers on buy-here-pay-here lots down around a grand . . . friend of mine buys salvage cars at auction, and pays about $300 for one, then he sells the engine and scraps the rest.
Best Regards,
Mike/Florida
..Keep fishing though you might catch a whopper..
