The Peterbilt 379 is the only semi in this game, which is quite disappointing because the developers could've had some more thinking and at least made a few more semis in the game. It's also one of the most common trucks you'd see in many medias, because tell me, you've obviously seen a truck exactly like this in a movie or another video game, right?
Overall, the truck has decent acceleration, what I would say above average. It is very heavy, which makes it the perfect vehicle to go around and smash up shit. It has a wide turning radius because.... it's a truck, right?
Extra stuff that is probably not required but eh Edit
Most likely the most feared vehicle the police have ever dealt with, because it's strong enough to send their cars or others flying with little effort.
Tanner, Badhand, Fabiene (or however it is spelled) owns one of thier own versions of this truck. Badhand drives this truck in a mission where you have to load up three cars into the back of a Haul-U trailer. Fabiene owns one, but hers got bombed. Tanner owns one and can drive it in any of the 3 cities.
The Timmy's own their own fleet of Peterbilts and they use them to ram and kill you. They are somehow nimble when they're not supposed to be, and their super speed makes them lightweight for some reason. They explode if they touch the water, which is some really dangerous shit right there, as you can also die in the water even when your head is above it. All this just tells you that the developers never knew basic science, or the water is toxic, because water isn't supposed to be explosive.