5. GM, 1981

Defect: Rear-suspension bolt failure
Units affected: 5.82 million
Models affected: 1978-'1 Buick Century and Regal; Chevrolet El Camino, Malibu and Monte Carlo; GMC Caballero; Oldsmobile Cutlass; Pontiac Grand Prix and LeMans
Date: February 1981
NHTSA campaign number: 81V025000
What happened: Whether a car is front-wheel drive or rear-wheel drive, independent or solid axle, its rear wheels don't just travel in forward and reverse, they also have to travel up and down to soak up bumps and keep passengers comfortable, all while remaining firmly mounted to the chassis. That's where it gets tricky. If any part of the rear suspension fails at speed, the probability of passenger drama is high. With this in mind, GM agreed to replace rear-control-arm bolts on a number of models in early 1980s, when reports surfaced that the bolts could fracture or loosen, leading to a loss of control.

4. Toyota, 2010

Defect: Unintended acceleration
Units affected: 6.67 million
Models affected: 2004-'10 Toyota Avalon, Camry, Corolla, Corolla Matrix, Highlander, Prius, RAV4, Tacoma, Tundra; various Lexus models
Date: October 2009 and January 2010
NHTSA campaign numbers: 09V38800, 10V017000
What happened: One issue, two recalls. Reports of unintended acceleration are mechanical enigmas. They are difficult to re-create in a service environment and easy to blame on driver error. Toyota ended up issuing two recalls in this case, one for a misplaced or incorrect floor mat that could jam the accelerator pedal, and one for a possible sticky accelerator-pedal mechanism.

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3. GM, 1971

Defect: Engine-mount failure
Units affected: 6.7 million
Models affected: 1965-'70 Chevrolet Bel Air, Brookwood, Camaro, Caprice, Chevy II, G Series, Impala, Kingswood, Nova, P Series, C Series and Townsman; GMC C Series, G Series and P Series
Date: December 1971
NHTSA campaign number: 71V235000
What happened: Motor mounts seem almost destined to fail. They have to be tough enough to keep a weighty engine in place, yet soft and pliable enough to allow for flex and to prevent the transfer of vibration to the vehicle's occupants. But when more than just a random amount of GM mounts started crumbling in the early 1970s, both GM and NHSTA knew something was up. After some back and forth, GM issued the recall before NHSTA made it official. Curiously, the official GM fix didn't include replacing the mounts, but simply anchored the engine to the firewall with a cable to prevent the engine from moving under mount failure, a situation that often resulted in unintended and uncontrollable acceleration.

2. Ford, 1996

Defect: Faulty ignition switch
Units affected: 7.9 million
Models affected: 1988-'93 Ford Aerostar, Bronco, Crown Victoria, Escort, Mustang, Tempo and Thunderbird; Ford F-Series trucks; Lincoln Town Car; Mercury Cougar, Grand Marquis and Topaz
Date: April 1996
NHTSA campaign number: 96V071000
What happened: By the mid-1990s, it had become apparent that the ignition switches in numerous Ford products were taking the idea of ignition too literally. There were reports of switch self-ignition, which caused electrical shorts and steering-column meltdowns. Nearly 8 million vehicles were affected by the time the offending ignition switch was phased out.

1. Ford, 2009

Defect: Cruise-control switch spontaneous combustion
Units affected: More than 14 million
Models affected: 1992-2003 Ford Explorer, Excursion, Ranger, Windstar, E-150 - 450 and F-150 - 450; Mercury Mountaineer.
Date: October 2009
NHTSA campaign number: 09V399000
What happened: The largest recall in automotive history originated with faulty cruise-control switches that were a possible fire hazard. The switches were prone to overheating, smoking or even burning, often hours after the vehicle had been parked. To complicate matters in certain models, the cruise-control meltdown would spread to the anti-lock braking system, requiring further inspection. Although the original recall affected only 4.5 million customers, an estimated 14 million vehicles were ultimately recalled.

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Andrew Wendler is an entrepreneur and journalist based in South Detroit. A former editor of the now-defunct MPHMagazine, his work has appeared in Car and Driver, Edmunds Inside Line and Hot Rod, among others. When not writing, you'll find him wrenching, racing, or on occasion, tour-managing a rock-music combo.

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