The actor's "death, and all other injuries or damages claimed, were the result of (his) own comparative fault," court documents filed by the car company last week said.
Walker was best known for his role as Brian O'Conner in the "Fast & Furious" franchise. His life was cut short when a Porsche he was riding in crashed on November 30, 2013, during a few days off in the filming of the seventh movie in the popular series. He was 40.
In September, Walker's daughter filed a wrongful death lawsuit against Porsche, claiming the sports car he was riding in had multiple design flaws.
But Porsche said the car "was abused and altered after being placed into the stream of commerce in a manner that was not reasonably foreseeable to (Porsche Cars North America)."
It went on to say that Walker was "a knowledgeable and sophisticated user" who knowingly exposed himself to the risks involved in using the vehicle.
The wrongful death lawsuit, filed on behalf of Walker's daughter, 16-year-old Meadow Rain, seeks unspecified damages for defects it alleges contributed to her father's death.
"The bottom line is that the Porsche Carrera GT is a dangerous car. It doesn't belong on the street," Walker's attorney, Jeff Milam, said in a statement at the time. "And we shouldn't be without Paul Walker or his friend, Roger Rodas."
The lawsuit alleges "the vehicle lacked safety features that are found on well-designed racing cars or even Porsche's least expensive road cars -- features that could have prevented the accident or, at a minimum, allowed Paul Walker to survive the crash."
An investigation by the Los Angeles County Sheriff's Department said it was speed that killed the "Fast & Furious" star.
"Investigators determined the cause of the fatal solo-vehicle collision was unsafe speed for the roadway conditions," Los Angeles County Sheriff's Commander Mike Parker said in March 2014.
The high-performance vehicle was going "between 80 and 93 mph at the time the car impacted a power pole and several trees," the report said. The posted speed limit on the Santa Clarita, California, office park road was 45 mph.
The sheriff's conclusion was no surprise, since the coroner's report previously estimated the car was speeding at 100 mph.
A source familiar with the Walker family's lawsuit, however, say that investigators who analyzed surveillance video think the car was actually going slower. The suit, in fact, claims the vehicle was traveling "at approximately 63 to 71 mph when it suddenly went out of control."
The family's investigators think the car was going between 40 and 60 mph at the point of impact, according to the source.
Possibly to explain the damage to the car in a lower-speed accident, the suit says the doors on the Porsche used "side door reinforcement bars that lacked adequate welds and consisted of material weaker in strength than what is used in popular mass-market cars ... designed and built to be operated at speeds much slower than the Carrera GT."
Last year's sheriff's investigation came to some additional conclusions.
Walker and friend Rodas, 38, had no drugs or alcohol in their blood. Both men were wearing seat belts. The airbags deployed as they should have when the car clipped a light pole and several trees, investigators said.
Nothing mechanical went wrong to cause the Porsche to leave the wide road. Investigators found "no pre-existing conditions that would have caused this collision," the report said. Experts from Porsche and Michelin were consulted
Walker and Rodas, racing team partners, left a charity event at a car shop co-owned by the men to take a ride in an office park in the community of Valencia in Santa Clarita, about 30 miles north of Hollywood. The crash happened a few hundred yards away.
An autopsy revealed "scant soot" in Walker's trachea, suggesting his life ended before the smoke and fire engulfed the car.
The actor's body was badly burned "and in a pugilistic stance. His right wrist was fractured and his left arm was fractured," the report said. Rodas was also described as in "a pugilistic" -- or defensive -- position.
Walker suffered fractures of his left jawbone, collarbone, pelvis, ribs and spine, the report said.
Rodas "rapidly died of severe blunt head, neck and chest trauma," the report said.
Walker's death came during a Thanksgiving break in filming of "Fast and Furious 7." The movie was completed using scenes already filmed by Walker
and scenes shot using his brothers as body doubles.