One of the last great American gas guzzlers.
318 refers to the displacement in cubic inches (CID) of a Chrysler small block V8 engine that has been around for ever. How long is forever? Well the first 318 as we know it today rolled off the line in 1967 and it is still in production today. (Although it's worth noting that there has been a 318 in production since 1957, but the earlier version shares nothing more than size with the '67 version.) Originally used as a car engine, it is now sold exclusively in trucks, jeeps and vans.
In over the course of the thirty or so years this engine has been in production it hasn't changed much. Other than it's conversion to EFI in the late 80's it remains the same pushrod small-block your parents knew and loved.
So why would anyone want one of these iron dinosaurs under the hood when they could have some swanky new PGMFI DOHC VTEC (Magic occurs here) Honda type thing instead? Well no one would keep an engine around this long if it never lived past the end of the warrantee. The 318 is a reliable workhorse, rarely breaking down, simple and cheep (relatively speaking) to fix when it does. It also produces a boatload of torque, which will come in handy if you want to move say a load of wood or sand sometime.
and now for a bit of a rant:
318 CID comes out to approximately 5.2L, which is what you will find in the glossy sales brochure for your glossy new pickup truck. However, the proper name is still "318." If you really want to fit in with the crowd you have just joined, with your purchase of a piece of American automotive history, you will now have to begin referring to all oldschool American engines by their sizes in cubic inches. Just accept, I know that the metric system makes more sense, but arguing with a 426 Hemi will get you nowhere.
With that out of the way, there is the down side of the abominable fuel economy. No really, the suckers are thirsty, like 20Mpg on the highway (UK gallons no less).