Part of the experience of owning these cars was the constant engine maintenance. One of the best books about servicing the car was by John Muir, an aging hippie auto mechanic. His writing exhorted us to keep the engine clean. The shadetree mechanic won't mind doing a quick oil change if he doesn't get filthy in the process. Muir's words hold wisdom for programmers.
Clean code is a joy to maintain.
It's clear what each line does, and there's little worry that a minor change will cause major problems in some other part of the system. Above all, clean code is pretty. Pretty code follows some indentation standard, so the structure is visible with a glance. Pretty code is never overly indented - twelve nested IFs are too many for any mere mortal to understand. One of C's weaknesses is its free form - it does not encourage pretty comments.