Gene.
Type of travel and climatology/weather are important factors in
determining propulsion efficiency as you indicate.
Three years ago I traveled to New England and back from Washington DC in
my 05 1.5 L Prius - Interstates at about 65 mph going north and via the
mountains at variable speeds on return. I got more than 49 mpg over 1400
miles.
City and urban driving will give you more mpg than highway driving
providing the HVAC is not used. Use of the HVAC will decrease mpg during
hot and cold days since the HVAC needs energy to operate during those days
while sitting in stopped traffic. During hot and cold days, highway driving
at 50+ mph will get you about the same mpg as city/urban driving since
excess energy not used to propel the car to maintain those speeds is used to
recharge the battery to provide torque for good acceleration at high speeds.
How one drives is also a major factor in fuel efficiency of any vehicle.
Stan Doore
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[email protected]>
Sent: Tuesday, June 24, 2008 1:49 PM
Subject: [USMA:41218] Re: LTE - Hybrid & Diesel Economy Math
Stan,
Another important key is driving profile. City stop-and-go vs. open road,
up and down mountains vs. level roads, and prevailing winds. Distance,
fuel consumed, and cost per unit of fuel for a year are *not sufficient*
for comparing vehicle performances.
Gene.
- Original message ----
Date: Mon, 23 Jun 2008 14:17:16 -0400
From: "STANLEY DOORE" <[EMAIL PROTECTED]>
Subject: [USMA:41201] LTE - Hybrid & Diesel Economy Math
To: "U.S. Metric Association" <[email protected]>
"Hybrids and diesels save, but math can be
tricky" in the June 20 issue of The Washington Times
explains various elements to be considered in
evaluating auto purchases; however, they are not
easy to use.
Consider standardizing on some basic numbers.
For example, use 10,000 km and 20,000 km (6200 miles
and 12,400 miles respectively) driven per year.
Then use the price of $4.00/gallon for gasoline and
$4.50 for diesel fuel to drive those distances.
These round numbers simplify the math and will help
people to understand the differences in savings
quicker.
The keys are total distance driven, fuel used
and the cost of fuel. Although miles per gallon or
km/L has increased for new diesel fuel vehicles, it
doesn't tell the full story about the additional
cost compared with gasoline hybrids.
Hybrids with electric drive provide added torque
and better fuel economy than new diesel powered
vehicles. And with an electric plug-in
option, hybrids will have even better fuel economy
compared with diesel only vehicles.
Stan Doore
