Weight reduction - not always good?

[Bill in Houston]

On the gently rolling hills north and west here, a really heavy car could P&G with the flow of traffic, since a heavy car will keep its speed up well on a slight hill (as compared to a light one).

But, your mileage would get killed in traffic...

[rvanengen]

Hmm...this brings back memories of when I used to drive a bus. We were on a charter trip, and after fueling my bus, I found that the batteries were dead. We needed to move the bus away from the fuel pump since it would be a few hours before the repair crew would arrive. One of the older drivers told me to pop it in neutral (this is a Greyhound size bus!) and laughed when I looked at him like he was crazy when he said we would just push the bus a few hundred feet away on level ground.

Well...we did push it, and I had to RUN once it was up to speed to get back in the driver's seat. It was MUCH MUCH easier to push that bus than ANY car I have ever owned. Talk about a lack of rolling resistance...and this is a 28000lb bus! This tells me that it was less than a horsepower to overcome RR on this vehicle, but on the interstate, it is almost 100% air resistance (shaped like a beveled brick).