Coast to coast

In a discussion with a fellow diesel enthusiast, I asked, why would Ford and Chevy would use a V-8 diesel engine in their light-duty trucks? http://www.gm.com/automotive/gmpowertrain/engines/duramax/index.htm
http://en.wikipedia.org/wiki/Ford_Power_Stroke_engine
The wikipedia article says, the (Navistar International built) Powerstroke engine is based off a gas V-8 engine design, but if you look at International's Class 8 truck engines, you will see they are inline 6 cylinder. http://129.33.208.100/maxxforce/products/class.aspx?classid=3

In fact, most, if not all 18 wheelers use inline 6 architecture. http://ohe.cat.com/cda/layout?m=85523&x=7 http://www.detroitdiesel.com/engines/series60/specs.aspx
Now, if Caterpillar and Detroit Diesel use an I-6 for a 600 hp tractor engine, why would you put a V-8 in a 250 hp pickup?

Dodge, has, for generations used the Cummins 5.9 liter I-6, with mind numbing results.

The reason the topic of Diesel engines even came up, was, the fuel efficiency of the Cummins powered Dodge trucks, as opposed to the Ford and GM diesels. Two of my friends have recently bought Dodge diesel trucks and during a trip to Worcester on Friday we were getting from 17-18 mpg in a 2007 Ram 3500 crew cab, short bed (automatic) - towing a 3000 pound trailer, going 75-80 mph. Dodge also offers a 6 speed manual transmission which offers even better fuel economy-upwards of 25 mpg, i'm told.


Here is an article about "The Most powerful Diesel Engine in the World", pretty interesting.
http://people.bath.ac.uk/ccsshb/12cyl/