Let’s say a person lives in a small town and makes frequent short trips- so short that the engine does not heat up all the way to the normal operating temperature. What effect(s) might this have on the engine? Could this cause carbon to build up inside the combustion chamber??
Although modern engines handle this a lot better than the old technology, I would still give the car an occasional “Italian” tuneup. That is, take it out for a long drive and open that sucker up.
Much of the wear to an engine is from cold starts, so if this is waht the car is normally subjected to I would switch to synthetic oil (like Mobil 1) which flows much better when cold. It’s more expensive, but you could lenghten the interval between oil changes.
You might also want to occasionally use the Techron additive to your gas to help with deposits (once or twice a year).
A big problem with only short trips is on the exhaust system. Without getting up to temp, water forms in the exhaust and remains in the pipes and muffler, rusting them out. A friend who only commuted 2 miles to work had to replace his muffler every two years.