Mileage @ MPH and RPM
02-20-2007, 07:38 PM
#11
Senior Member
Join Date: 10-06-2006
Location: Delaware Shore
Posts: 162
02-20-2007, 08:19 PM
#12
Member
Join Date: 04-17-2006
Location: Saginaw, MI
Posts: 46
Assuming you have an automatic transmission and the shift lever is positioned in "Drive" with your cruise control engaged, please advise as to you engine RPM at 55 MPH and 64 MPH?
Without question, as you increase your MPH, so will your engine RPM, however your MPG will begin decrease above a certain speed.
I drive all highway miles, 34,000 miles in 9 months; I can tell you for a fact my fuel mileage begins to decrease a bit at highway speeds greater than 55 MPH, especially at speeds greater than 60 MPH.
I have tried all sorts of speed combinations to increase my fuel mileage and decided to just drive at the posted speed limit, traffic and weather conditions permitting.
My highway driving conditions are optimal, in the summer months I can pull 33-34 MPH consistently. My winter mileage drops significantly right along with the ambient temperature.
Regards,
HHRANDY
Without question, as you increase your MPH, so will your engine RPM, however your MPG will begin decrease above a certain speed.
I drive all highway miles, 34,000 miles in 9 months; I can tell you for a fact my fuel mileage begins to decrease a bit at highway speeds greater than 55 MPH, especially at speeds greater than 60 MPH.
I have tried all sorts of speed combinations to increase my fuel mileage and decided to just drive at the posted speed limit, traffic and weather conditions permitting.
My highway driving conditions are optimal, in the summer months I can pull 33-34 MPH consistently. My winter mileage drops significantly right along with the ambient temperature.
Regards,
HHRANDY
03-22-2008, 06:36 PM
#14
New Member
Join Date: 10-19-2006
Location: Georgia
Posts: 28
My actual mileage is always lower than the DIC indicates. Filled up today with the DIC showing 31mpg. Actual miles/gallons shows 29.5 . Sometimes the spread is greater. Weird thing is, that was 1/2 tank commuting and 1/2 tank highway! This car gets well above EPA estimates in my experience. My bosse's Hundae is rated at 25/34 and she gets 19commute/25 highway. Gotta love this car. Oh Yea, that highway run was at 75 mph on cruise. 2.2L auto
03-22-2008, 08:20 PM
#15
Senior Member
Join Date: 12-14-2007
Location: Orlando, Florida
Posts: 246
Its all about the efficiency of the engine. My car also does better at 65-70 mph. The engine operates better at 2500-3000 rpm than at 1500-2000 rpm. It was explained to me by an engineer but I dont remember his explanation well enough to get it right, maybe another member with more smarts than me can explain it.
03-24-2008, 10:23 PM
#18
Senior Member
Join Date: 05-22-2007
Location: Huntington Beach, CA
Posts: 318
The engine is running more efficently at a certain RPM. How? The air going into the engine is being sucked in at a higher rate, thus causing a better mixing of fuel and air. The fuel is burned more complete and effeciently, so your mpg will go up. This is only good up to a certain a certain engine speed as the air resistance around the HHR at higher speeds will cause lower fuel economy. The "sweet spot" will change in variance to ambient air temperature, pressure, humidity, and elevation so the results my be different for everyone.
OK Guys and Gals,
This defies all of my logic.
At 55 MPH with cruise control on I can average 26/27 Miles Per Gallon.
At 64 MPH with cruise control on I can averarge 32/33 MilesPer Gallon.
This defies all of the published logic as to lower speed creates better mileage and/or coeficient of friction.
Has anyone had the same experience?
2.4 liter ecodive 2LT. -Sunburst Sam
This defies all of my logic.
At 55 MPH with cruise control on I can average 26/27 Miles Per Gallon.
At 64 MPH with cruise control on I can averarge 32/33 MilesPer Gallon.
This defies all of the published logic as to lower speed creates better mileage and/or coeficient of friction.
Has anyone had the same experience?
2.4 liter ecodive 2LT. -Sunburst Sam
03-24-2008, 11:50 PM
#19
Senior Member
Join Date: 11-10-2007
Location: Summerville / Clemson, SC
Posts: 217
between 60~65, i'd say i get 32mpg...up to 34mpg sometimes.
between 68~72, it's probably around 28-30 mpg.
75-80, it's down around 26-28
these are just my rough numbers tracking the DIC from my trips to/from college on the interstate, in my 2.2L automatic. last time i actually checked the miles, the DIC overstated the mpg by about 0.3. oh well.
between 68~72, it's probably around 28-30 mpg.
75-80, it's down around 26-28
these are just my rough numbers tracking the DIC from my trips to/from college on the interstate, in my 2.2L automatic. last time i actually checked the miles, the DIC overstated the mpg by about 0.3. oh well.
03-28-2008, 08:41 PM
#20
Senior Member
Join Date: 03-27-2008
Location: New Mexico
Posts: 132
Well making sense of this scenario, My 4x4 ford which got traded in for this HHR, I had since 92 with 190000 miles and around 8mpg. I filled it up once a week with my normal driving scenario.
With this HHR the computer shows me at 22mpg and I am filling up ever 2 weeks. Now add the loss in numbers due to altitude, If i were around sea level, I'd be at about 26mpg around town
With this HHR the computer shows me at 22mpg and I am filling up ever 2 weeks. Now add the loss in numbers due to altitude, If i were around sea level, I'd be at about 26mpg around town