The complaint counts are nearly tied. The failure modes are not even close.

The loudest driveability item in the 2021 file. The 3.5-liter V6 paired with the six-speed automatic can hunt for gears — owners describe it seeking between 5th and 6th on cruise control and occasionally over-revving toward redline — and the truck can feel gutless off the initial throttle until it downshifts. A Toyota master tech frames the generation's surging and shift feel as software-and-fluid rather than a failing transmission (an engine-computer update addresses surging; torque-converter shudder ties to fluid condition, so keep it fresh at 60k/6-year intervals). Test-drive it on the highway and at low speed to judge whether the feel bothers you.

Sources: NHTSA complaint database, 2021 Tacoma · Independent mechanic/owner channel transcripts (3rd-gen Tacoma, incl. The Car Care Nut)

Although the fuel-pump safety recall does not reach 2021, some owners report a noisy fuel pump, extended cranking on cold starts, or an isolated stall. There is no recall on the 2021, so these are diagnose-on-symptom items rather than a known campaign — and Toyota's separate high-pressure-fuel-pump coverage program (for a fuel odor originating at that pump) spans 2016–2022 model years. Listen for pump noise at startup and note any hard-start behavior on the test drive.

Sources: NHTSA complaint database, 2021 Tacoma · NHTSA recalls (verified-zero reconciliation) and manufacturer communications (SSC 22TC01; CSP 23TE08)

The V6's plastic coolant-bypass pipe behind the engine can crack — check the passenger side and top of the transmission for a coolant trail; it's a labor-heavy job, covered under powertrain warranty while in term. On Double Cab trucks, Toyota has a service bulletin for a rear-differential whine around 50 mph caused by vibration transferring through the chassis — it's characteristic, not a failure. A couple of 2021 owners did report needing rear-differential replacements, but that's an outlier in a small file, not a pattern.

Sources: NHTSA complaint database, 2021 Tacoma · Independent mechanic/owner channel transcripts (3rd-gen Tacoma, incl. The Car Care Nut)

The defining failure of this model year and the reason it is not a quiet truck. The mechanical vacuum pump that provides brake assist is driven off the camshaft. When it fails, two things happen at once. The brake pedal goes rock-hard with no warning and almost no assist — one owner ran a red light, another had to use the parking brake and downshifting to stop from 40 mph, another describes his wife panicking that she had no brakes at 20 mph on a hill. And because of how it is driven, the seizing pump can break the exhaust camshaft and push metal into the engine. One owner: the pump "shattered and pieces of metal went into my engine." Another, at under 50,000 miles: "complete brake failure caused by vacuum pump failure — the vacuum pump failure led to irreparable internal engine damage, requiring complete engine replacement." A third had the camshaft fixed first and then found the brakes still did not work. One filing states this is the fifth 2.5-litre truck the writer knows of with the same sequence. There is no NHTSA recall and no GM Colorado programme covering it — GM's 19V645 vacuum-pump recall and Special Coverage N182202780 apply to full-size 5.3- and 6.2-litre V8 trucks and name a different pump on a different engine. Treat pedal feel as the primary inspection item on any 2.5-litre 2021.

Sources: NHTSA complaint database, 2021 Chevrolet Colorado (true count 69) · NHTSA recall database, 2021 Chevrolet Colorado (recall 20V811)

A second engine thread, smaller but severe. One owner reports "catastrophic engine failure of a 2021 Colorado 3.6L V6" that began with a misfire on a congested street and ended with GM replacing the engine. Another describes complete engine failure attributed to a defective crankshaft, with the truck sitting at a dealer unanswered for 24 days. A third was quoted $6,500 before tax simply to diagnose an engine that started shaking and threw engine, electrical and stability warnings at once. And a fourth reports code P0014 with oil pushed through the bank 1 camshaft solenoid actuator, replaced, then the light returning. None of these has a recall or a Colorado-specific programme behind it. Have a compression and oil-condition check done on any V6 you are serious about.

Sources: NHTSA complaint database, 2021 Chevrolet Colorado (true count 69)

A cluster with a specific location. Owners report a coolant leak from the hoses running to the thermostat housing with no accident and no visible hose damage — one adding that it has been "commonly reported amongst the same vehicles across the country." Another reports the coolant temperature gauge stuck at around 160 degrees with the cooling fans at high speed constantly, because the thermostat is stuck open, on a truck with under 100,000 miles. Neither is expensive on its own; both are cheap to spot. Look for dried coolant crust around the thermostat housing, check the gauge reaches normal operating temperature on the drive, and listen for the fans after shutdown.

Sources: NHTSA complaint database, 2021 Chevrolet Colorado (true count 69)