Date: Sat, 29 Mar 2003 19:22:44 -0000 From: "DervMan" <dervmannopsamail.com> Subject: Re: Low 9-5 Gas Mileage
"no-spam" <nonopsamo> wrote in message news:b64rfl$rm3$1nopsam.chatlink.com... > I have a 2002 9-5 Wagon (4-cylinder, 2.3t, automatic, about 5,000 miles) that gets about 19mpg in town (mostly short trips), but on > the highway gets upper 20's. On long trips, I have even seen 28+mpg. > > This behavior seems odd to me; I was expecting to see low 20's in town. Why is there such a huge discrepancy between city and > highway? I frequently reset the trip computer in order to get a more accurate calculation. I never drive in Sport mode, and was > wondering if that made a difference. (Would I get better mileage in Sport mode?) > > I did see a graph in the owner's manual that showed increased fuel consumption at low temperatures, but being in the mid-south, I > did not think that was much of an issue. > > Any ideas? Because internal combustion engines are far more efficient when working at a steady engine speed. Changes in speed (well, increases) knacker fuel consumption. A car might be making 50 mpg at a steady 50 mph, but if it's accelerating through 50 mph, it may only be making 25 mpg, or less. Furthermore, short trips are not good for either the engine or fuel consumption, since the engine is cold and therefore running a richer fuel mixture. Check out my site, specifically the bit on fuel consumption, then look at the charts, for Kermit and my previous cars. It's easy to see what tanks are just about solely in the city, which ones are outside, and which one are inbetween. Anything over 40 mpg is mainly out of town, anything under about 35 mpg is pretty much in town . . . -- The DervMan www.dervman.com
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