986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

MNBoxster · 05-25-2006, 11:31 AM

Hi,

Many variables affect your actual MPG. These can include Tire Pressure, your Driving Style (it doesn't take too many hard take-offs to put the MPG in the toidy), the terrain where you drive (Hilly, Flat), Wind (if you live in a Windy area, this will have an effect), the type and condition of your local roads (increased/decreased rolling resistance), the current Health of your Car and how well you maintain it, your own weight and that of your avg. passenger, even how many and how often you use the accessories - including the CD Player, how much stuff you haul in the trunk(s), the Wheels and Tires you use, and as SD987 points out, whether you are Top Up or Top Down.

In any event, consistency is the key to maxing your MPG. With a range of 300+ miles/Tank, just a few spirited miles or starts or varying your driving practices just a little can have a tremendously negative effect.

You cannot rely on the Manufactuers reported MPG because these are accumulated under Ideal conditions, even greater than Ideal conditions. They use no accessories, no hard starts, in 75° Temperatures, avg. 48MPH and never go beyond 60MPH. The EPA even admits that these are misleading and rarely can be duplicated in Real-World driving.

In fact, the EPA has changed their testing for the '08 Model Year to more closely resemble real conditions and this is expected to lower the MPG ratings on cars by as much as 30% on the Consumer's Fuel Economy Sticker. Ironically, the DOT is not going to hold Manufacturers to these new Testing Standards to determine compliance with Government regulations (CAFE) requiring automakers to produce fleets averaging at least 27.5 mpg for cars and 21 mpg for light trucks, they will still use the old methods for determining this MPG. See an interesting article here:
http://www.nctimes.com/articles/2006/01/11/business/news/20_07_141_10_06.txt

I get about 19.4 MPG fairly consistently with my '99 TipS with a high of 32.3 on a long-distance, Cruise-controlled trip...

Happy Motoring!... Jim'99

05-25-2006, 11:31 AM	#11
MNBoxster Registered User Join Date: Sep 2005 Location: Minneapolis/St. Paul, Minnesota, USA Posts: 3,308	Hi, Many variables affect your actual MPG. These can include Tire Pressure, your Driving Style (it doesn't take too many hard take-offs to put the MPG in the toidy), the terrain where you drive (Hilly, Flat), Wind (if you live in a Windy area, this will have an effect), the type and condition of your local roads (increased/decreased rolling resistance), the current Health of your Car and how well you maintain it, your own weight and that of your avg. passenger, even how many and how often you use the accessories - including the CD Player, how much stuff you haul in the trunk(s), the Wheels and Tires you use, and as SD987 points out, whether you are Top Up or Top Down. In any event, consistency is the key to maxing your MPG. With a range of 300+ miles/Tank, just a few spirited miles or starts or varying your driving practices just a little can have a tremendously negative effect. You cannot rely on the Manufactuers reported MPG because these are accumulated under Ideal conditions, even greater than Ideal conditions. They use no accessories, no hard starts, in 75° Temperatures, avg. 48MPH and never go beyond 60MPH. The EPA even admits that these are misleading and rarely can be duplicated in Real-World driving. In fact, the EPA has changed their testing for the '08 Model Year to more closely resemble real conditions and this is expected to lower the MPG ratings on cars by as much as 30% on the Consumer's Fuel Economy Sticker. Ironically, the DOT is not going to hold Manufacturers to these new Testing Standards to determine compliance with Government regulations (CAFE) requiring automakers to produce fleets averaging at least 27.5 mpg for cars and 21 mpg for light trucks, they will still use the old methods for determining this MPG. See an interesting article here: http://www.nctimes.com/articles/2006/01/11/business/news/20_07_141_10_06.txt I get about 19.4 MPG fairly consistently with my '99 TipS with a high of 32.3 on a long-distance, Cruise-controlled trip... Happy Motoring!... Jim'99 Last edited by MNBoxster; 05-25-2006 at 12:03 PM.