The attorney for a young man charged with manslaughter in a fiery five-person fatal collision on Highway 101 two years ago is seeking a dismissal of the most serious charges, arguing there is insufficient evidence of his client?s alleged intoxication.

The judge in the criminal case against Ryan Karr considers that request Friday. And two days earlier, a recently filed civil lawsuit against Karr and both auto manufacturers will have its first hearing in Sonoma County court.

Judge Lawrence Antolini ruled after a preliminary hearing last summer that there was a strong suspicion to believe Karr, 28, of Windsor was intoxicated on Jan. 19, 2007, when his car rammed into the back of a Honda that had stopped during rush-hour traffic on northbound Highway 101.

Five members of a family died in an ensuing fire despite rescue attempts by passersby and law enforcement officers. The only survivor, Christian Flores Carlos, now 6, was severely burned and has since lost an arm, a leg and an ear to burn-related trauma, according to court records.

Karr faces misdemeanor and felony manslaughter charges. The ruling on intoxication is critical: The impairment aspect raises the manslaughter charges to felonies instead of misdemeanors.

A lawsuit filed in late December by family members of those killed name Karr, Honda and Mitsubishi, claiming negligence, wrongful death, product liability and personal injury.

The crash near Airport Boulevard killed Maria Lopez Camacho, 54, Almadelia Menera Basurto, 16, Edith Carlos Medina, 23, Fernando Flores Carlos, 7, all of Windsor, and Carmina Solorio, 23, of Mexico.

The suit seeks unspecified general and punitive damages against the two Japanese car companies and their American counterparts, in addition to damages stemming from Karr?s driving.

It alleges that the companies knew the designs of Karr?s 2001 Mitsubishi Eclipse and the family?s 1992 Honda Civic were dangerous ? particularly in collisions involving the fuel systems.

According to the CHP and witnesses, Karr?s Mitsubishi struck the back of the Honda, which erupted into flames, trapping the victims inside the burning car.

Witnesses and officers described the car bursting into a ?huge, huge ball of fire? moments after the collision and said flames reached 20 feet high. A police officer testified that he smelled gas and saw roiling black smoke and dark orange flames as people tried to rescue the occupants. Other would-be rescuers said they were pushed back by the intense heat.

The civil suit was filed by Santa Rosa attorney Pat Emery and Bob Langdon of Missouri, who specializes in defective vehicle and product litigation. His firm has won several multi-million dollar verdicts in product liability and vehicle crash fatalities. The first hearing in the case is set for Wednesday.

In the 20-page lawsuit, the plaintiffs argue that Mitsubishi knew its Eclipse could cause serious damage to other vehicles, including the fuel systems, when it ?under rode? other cars in collisions. The suit also claims Honda knew the design of the Civic was ?known to be vulnerable to the compromise of its fuel containment system and resulting fires? in crashes.

?Despite such knowledge,? the suit claims, the companies sold the vehicles with disregard for passengers? safety and ?with knowledge that serious injury and death would result.?

Further hearings are set for April in the civil suit.

In the criminal case, Friday?s hearing will seek a ruling on whether there is sufficient evidence to show that Karr was too impaired to drive on the day of the crash.

In a preliminary hearing in August, conflicting evidence about Karr?s alleged intoxication caused concern for the judge, who tried to pin down a prosecution toxicologist about whether Karr?s ability to drive was impaired ? not just whether a drug test showed traces of cocaine and marijuana.

The local CHP?s top drug-recognition experts concluded that Karr was impaired by cocaine, but not marijuana.

But a state toxicologist testified that the cocaine use was too many hours before the crash to have impaired Karr. He said the marijuana use was also several hours before but, when pressed by Antolini, couldn?t say for certain whether Karr was impaired by the depressant.

Karr tested negative for alcohol use.

Prosecutors argue that they showed enough evidence that Karr was impaired, perhaps by multiple drugs that caused mixed symptoms.

Karr has said he was momentarily distracted and looked up too late to stop before hitting the car ahead of him.

A CHP officer testified that Karr performed poorly on sobriety tests she administered at the scene, yet she didn?t arrest him. Charges were filed almost a year later.

Karr remains free on bail.