Why do people spell Cummins with a "ings" ?

This does irritate me because I used to work for Cummins. Just recently I have been watching a television commercial from a local Nissan dealer talking about the new Titan pickup where in both the spoken and written wording they say Cummings right at the point where they are showing the Cummins badge on the side of the truck.

It just seems to go along with the dumbing down of people and the don't care attitude.