A quiet, recall-light 4Runner where the only real homework is the highway shimmy and a couple of $200 door-lock actuators.

A recurring 4Runner annoyance shows up on 2021 cars: door-lock actuators failing one after another — front doors and the liftgate — at roughly a $200 part each, out of warranty once the bumper-to-bumper expires. Owners cite a class-action over the pattern. It's not a safety defect, but it's a nagging, repeating bill. Operate every lock from the fob and the switch before buying.

Two generation-wide items in the 2021 file. The sunroof can shatter spontaneously ('sounded like a gunshot,' glass blowing outward) with no recall — comprehensive insurance is the backstop. And the brakes feel soft and nose-dive by design, with real but low-frequency reports of the pedal sinking or briefly losing braking; test braking from 30 mph and watch the pedal hold at a stop. TRD Pro trucks add a cold-weather Fox-shock clunk covered by a Toyota bulletin.

On four-wheel-drive 2021s, a cyclical groan from the front differential heard only in two-wheel drive (gone in four-wheel drive) is a known, inexpensive fix — a front-differential needle bearing with an updated part. A separate rear-differential groan is benign; a master tech says to keep the fluid fresh and drive it. If you hear the front groan, negotiate rather than worry.

The generation-wide inspection: salt-belt frames rust, and a rotten frame is a walk-away because replacing it costs more than the truck. The rear hatch rusts under its plastic trim. A 2021 is young, but a northern-climate truck still deserves an underside look before you assume it's clean.