At the suburban Chicago RV show one dealer sales person told me that the on-board computer in the Cat 300 diesel would take about 3 years to gain maximum fuel efficiency and that it would improve as it learned our driving habits. Was he smoking something or is there some truth to this?

Thanks.

George:

Allison Transmission computers learn a lot faster than that, normally under 2,000 miles of driving. First I have heard of the engine computer learning like that. Many diesels do not hit their stride for 15,000 to 50,000 miles and that is often three years of usage. I figure you are dealing with a salesperson who knows enough to say dangerous things.

Once again Bill is right.  I believe it is the engine itself rather than the computer, that will take three years of normal use in and RV to reach its maximum performance.  The engines in the diesel pushers are long mileage engines and may take up to 50,000 miles to reach maximum power and fuel economy. 

Many times an informed sales person has difficulty knowing just how technical to get with a prospective buyer, so they may say some things that sound a little off to an informed and technically oriented buyer.  Hopefully that was the case here.  Of course there are also some sales people who don't have a clue and will say anything they think might convince you to buy.  Take what they say with a grain of salt and do your own research.