DALLAS (AP) _ A man described as a hot-tempered driver was convicted Friday of fatally shooting a fellow commuter on the city's busiest highway, and sentenced to the maximum 20-year prison term.

The jury took nearly 10 hours to find Deno Victor Loredo, 27, of Dallas guilty of voluntary manslaughter, but only 30 minutes to decide his punishment for the Feb. 18 death of Jack Vaughn of Fort Worth.

The penalty for voluntary manslaughter ranges from two to 20 years.

The prosecution had portrayed Loredo as a quick-tempered driver, but the defense said he was just trying to defend his family.

Vaughn, 38, and his stepson, Larry Evans Jr., were on their way to work at a North Dallas construction site when Vaughn was shot in the head as he sat on the passsenger side of their car on busy Central Expressway.

Bill Rice, Loredo's lawyer, argued Thursday that Loredo endured a ''three- minute ride of terror'' caused by Vaughn and Evans and was only trying to defend his family.

''Can't you just see those two guys (Vaughn and Evans) having a good old time with a carload of Mexicans?'' Rice asked jurors. ''Deno Loredo did what anyone with a 1-year-old child and wife would do.''

But prosecutors said Loredo had a ''hair-trigger temper'' that was sparked by minor traffic problems and possibly drunkenness.

''There was no ride of terror. There was an act of an irrational man who shot another man,'' said prosecutor Marshall Gandy.

Gandy said Loredo, after partying all night, started the confrontation with Vaughn and Evans when they passed his car before reaching Central Expressway, where the early-morning shooting occurred.

Gandy also disputed Loredo's testimony that he displayed his handgun to the two men to scare them away, and that the gun accidentally went off when he hit a curb.

Loredo said Evans tried to run him off the road, but Evans denied the charge.

''They (Vaughn and Evans) were laughing at us,'' Loredo testified. ''They kept harassing me, throwing me obscene gestures. I was scared and fearing for my family. I was just trying to get them off my back.''