When Toyota announced last week that it was halting sales and production of models associated with unintended acceleration, owners of the Toyota Prius, Camry Hybrid, and Highlander Hybrid, as well as Lexus hybrid owners, were somewhat relieved. That’s because the hybrid models were not included in the list of affected models.

Toyota said the problematic pedals found on conventional models are provided by CTS Automotive Products, while a different supplier, Denso Corporation, supplies the accelerator pedals for Toyota hybrids. As a result, the assembly line for the Camry Hybrid has remained online at Toyota’s Kentucky plant, while the non-hybrid Camry in the same plant has been idled.

Sticking Pedal versus Pedal Floor Mat Entrapment

To add to the confusion, the Toyota Prius remains on a different recall list, first issued in September, when the company said it would reshape or replace accelerator pedals on 3.8 million vehicles. That recall involves 2004 to 2009 Priuses—and recent year models of the Camry, Avalon, Tacoma and Tundra, as well as Lexus models ES 350, IS 250, and IS 350. The correction is intended to reduce the risk that the pedal may be jammed in the floor mat. In addition, the company will replace original equipment floor mats with redesigned mats.

Mike Michels, Toyota vice-president of communications, informed HybridCars.com in an email:

“The sticking pedal issue does not affect Prius, but the pedal floor mat entrapment does involve Prius and there is a recall in the works to modify the cars to make them less likely to get entrapped by an out of place all weather floor mat.”

At the time of the floor mat recall—prior to the more recent recall involving the accelerator hardware—ABC News cited reports of 16 acceleration-related deaths and more than 200 accidents. It’s not clear if those accidents are attributed to a sticking pedal or the floor mat problem, or a combination of the two. At the time, Toyota said it had confidence the problem was linked to floor mats and not a vehicle design flaw or problems related to braking, fuel or accelerator systems.

Publicity Fuels Speculation

Confusion about the two different potential causes of the acceleration problem most recently has been confounded by a number of anecdotal stories concerning Priuses. Speaking at an event in San Francisco last week, Apple co-founder Steve Wozniak said that his 2010 Toyota Prius—not on either of the two recall lists—has “an accelerator that goes wild, but only under certain conditions of cruise control.” He said, “This is software. It’s not a bad accelerator pedal. It’s very scary, but luckily for me, I can hit the brakes,” he said.

The problem experienced by Wozniak, attributed using cruise control at high speeds, appears to be completely separate from other reported issues involving rapid acceleration from a standstill or the inability to stop despite the use of brakes. Toyota advises drivers experiencing the acceleration problem to put the vehicle into neutral, and to firmly plant both feet on the brakes.

John Hanson, national manager environmental safety and quality communications at Toyota, responded to Wozniak’s complaint, saying, “After many years of exhaustive testing, we have not found any evidence of an electronic [software] problem that would have led to unwanted acceleration.”

The highly publicized case has led other Prius drivers to submit their unintended acceleration stories to website forums. On Jan. 29, a visitor to PriusChat.com reported that his accelerator pedal got stuck twice over a two-year period, when after he “fully depressed forcefully” the accelerator when merging on to the freeway. “I do not have floor mats in my car,” he added.

In a separate inquiry initiated in late 2009, the National Highway Traffic Safety Administration responded to a few dozen complaints about the 2010 Toyota Prius’s braking performance. The Prius owners complained about a feeling that the car lurches forward when hitting a pothole or other uneven surfaces. These complaints were echoed by a number of visitors to HybridCars.com, although drivers of hybrids made by other automakers, complained about the same issue. NHTSA has not yet opened an official investigation into the 2010 Toyota Prius braking issue—which appears to be a minor safety concern compared to uncontrolled acceleration.

Some of the reports to NHTSA and websites appear to be random and isolated, but speculation that Toyota had not correctly identified the core and potentially fatal problem with runaway acceleration was further fanned today by Rep. Henry Waxman, D.-Calif., and Rep. Bart Stupak, D.-Mich. The congressmen questioned Toyota’s claims that sudden acceleration was due to “two different issues,” sticky gas pedals and poorly fitting floor mats. Waxman and Stupak demanded answers from Toyota by the end of the week.

Uncertainty Remains

The complicated and shifting explanations—and the increasing number of personal anecdotes and high-profile accusations—are likely to continue producing confusion and worry among Toyota drivers, including hybrid owners, even after various corrective measures are taken. Yet, Toyota asserts that it’s on track to fix the various problems. According to the Toyota website, “The condition is rare and does not occur suddenly.”

We will continue to monitor the situation and update this page with any additional information. Readers are encouraged to post their experiences in the comments on this page.