The Toyota Camry is still the best selling car in America but a growing number of Camry consumers are puzzled over the car's performance and unsure about Toyota quality.

A software problem, it seems, is slowing the new Camry when the driver mashes the gas pedal.

Bonnie in Milburn, New Jersey described the problem in a complaint to this way:

"We got a new 2007 Camry in August. From day one the car does not shift properly. It hesitates and sometimes when you push the accelerator it hesitates and it does not budge but then jerks. It can be dangerous if you think you have enough time to cross a street and car does not move."

Bonnie has taken her leased Camry back to her Toyota dealership three times.

"I am so fed up with this car. I don't want anymore," she said.

Internet chat rooms recently have swelled with similar consumer complaints prompting Toyota engineers to examine the 2007 Camry engine and powertrain in search of why the best-selling car in America loses power at times when power may be most needed.

The answer seems to be that the new Camry has a drive-by-wire system that remembers how a driver accelerates. So in response to an unexpected demand from consumers like Bonnie trying to navigate the busy roads of New Jersey, the Camry engine and transmissions may tend to hesitate.

That is because when an easy-going driver demands immediate power the software that controls the four-cylinder engine and five-speed automatic transmission can be momentarily confused, causing the Camry to bog down.

A service bulletin from Toyota is on the way to dealers with an software modification that is described as "easily accomplished according to a company spokesman. The dealership can tailor the engine and transmission software however a Camry owner wants, according to the company, but dealers will make the modification only if owners report a problem.

There is no 2007 Toyota Camry recall, at least not now.

Camry sales remain robust despite these performance difficulties. The 2007 car went on sale in March and supplies remain tight. Sales of the Camry in September were up 3.9 percent over the same month last year and Camry assembly plants are running at full capacity.

Camrys built after October 1 carry new software that does not slow engine and transmission performance, according to the company. Toyota says it doesn't know how many consumers driving the 2007 version of the best-selling car in America are riding around with the old software.