Streets that predate the car
Boston's street plan was not designed. It accumulated, on top of cow paths and filled harbour, over three centuries before anyone owned a car. Worcester, Salem and half the older towns are the same.
What that means mechanically is constant low-speed manoeuvring at or near full lock — into spaces, around corners with no radius, and through junctions that meet at angles nobody would draw on purpose.
Full lock is the hardest thing you can ask of an outer constant-velocity joint. The joint articulates furthest, the grease is worked hardest, and the boot flexes at its extreme. A car here reaches the rhythmic clicking that means a worn outer joint at a mileage a highway car would not.
Rotaries, and what they load
Rotary junctions are common here and rare almost everywhere else in America. They ask for continuous steering input under lateral load rather than the straight-ahead-then-turn pattern of a grid.
That loads the steering rack, the tie rod ends and the outer joints in a way a grid does not, and it does it at every trip. Combined with the salt, it is why steering components are a routine replacement here rather than a rarity.
Parallel parking removes mirrors
A city where most parking is on-street and most spaces are tight produces a specific repair list, and it is not a wear list. Mirrors clipped by passing traffic. Bumper covers scuffed making a space work. Wheels gouged against granite kerbs.
The wheel one matters more than it looks. A rim bent against a kerb at an angle still holds air and still looks fine, and it produces a vibration that survives every rebalance because balance was never the problem. Ask for a runout measurement before buying a second tyre.
Mirrors are worth ordering by part number rather than by description. On a modern car the housing carries the indicator, the puddle lamp, the heating element and often the blind-spot module, and "driver side mirror" describes a dozen different parts on one model.
The inspection dates it all
Every registered vehicle is inspected annually for safety and, on most, for emissions. Mirrors, lights, glass, tyres, brakes and suspension are all inspection items — which is exactly the list the streets have been working on.
A lit check engine light fails the emissions portion whatever the car is doing, and so does a set of readiness monitors that has not completed after somebody cleared a code. Setting them again takes a full drive cycle, which in a city of short journeys can take a fortnight.
Salt, on top of everything
The winter is long and the salting is heavy, so every failure above happens to a car whose underside is also corroding. The practical consequence is the salt-belt buying rule: in this climate the removal is the expensive half of a job, so the complete assembly usually beats the component.
A loaded caliper rather than a rebuild kit for one that is already pitted. A complete hub rather than a bearing pressed into a corroded knuckle. A complete strut rather than a bare damper on a lower bolt that has bonded into its sleeve.
Checked