How are semi truck engines different than other vehicles'?

Well, the'yre much, much bigger in every way. Most are simply inline 6 cylinder turbo diesels. They just have massive parts. They look like a regular small truck engine, just larger. read more

A Class B (any school bus), C (any urban-transit-vehicle or highway-coach), or D (heavy trucks other than tractor-trailers) license enables its holder to drive any truck-trailer combination with a registered- or actual-gross-vehicle-weight (i.e., including towing- and towed-vehicle) greater than 11 tonnes, that includes one trailer weighing no more than 4.6 tonnes. read more

Semi trucks make up just 15 percent of commercial trucks in the U.S., yet they travel 42 percent of all miles covered by commercial trucks. Large commercial trucks covered about a quarter of a trillion miles in 2006, while total vehicle miles were about 3 trillion. read more