Mpg at very high speeds?
11-14-2014, 01:39 AM
#1
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2013 Honda CRV
Mpg at very high speeds?
Ok so I'm still wondering how they managed to get 40mpg at a constant speed of 140mph here:
http://www.gizmag.com/go/4003/
According to my calculations, even a compact car with a .24 drag coefficient would get about 50mpg on a 100% efficient engine. So they're claiming that a full size car gets 40mpg with a heat engine? The engine would have to be 70% efficient and the car would have to magically reduce its drag coefficient (or shrink
) to get 40mpg at 140mph
Has anyone ever tried setting cruise control at 140mph and seeing what mpg they got? Does the car lower the suspension at high speeds (possible, but not enough of an efficiency boost)
http://www.gizmag.com/go/4003/
According to my calculations, even a compact car with a .24 drag coefficient would get about 50mpg on a 100% efficient engine. So they're claiming that a full size car gets 40mpg with a heat engine? The engine would have to be 70% efficient and the car would have to magically reduce its drag coefficient (or shrink
) to get 40mpg at 140mphHas anyone ever tried setting cruise control at 140mph and seeing what mpg they got? Does the car lower the suspension at high speeds (possible, but not enough of an efficiency boost)
11-14-2014, 02:09 PM
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'87 190D, '96 E300D (2), '07 ML320 CDI
Do the math:
"The vehicles were driven by three teams of six drivers, also including the former DTM contestant and current FIA Formula 1 Safety car driver Bernd Mayländer, with each driver taking the wheel for about 2 hours, 10 minutes between refuelling stops.
In total, the record drivers had to stop 966 times in the temporary pits set up alongside the track; refuelling and the obligatory visual check of the vehicle took around 2 minutes on average. Servicing, including the replacement of operating fluids and wear parts, was performed using the customary service interval indicator in the cockpit."
The 3 cars stopped 966 times for fuel. That is every 310 miles for each car. They have a 20 (21?) gallon tank. That is more like 16mpg, which is what one would expect.
They may go 140mph, and they may get 40mpg, but not at the same time. The article is either poorly worded, or just plain wrong in this regard.
"The vehicles were driven by three teams of six drivers, also including the former DTM contestant and current FIA Formula 1 Safety car driver Bernd Mayländer, with each driver taking the wheel for about 2 hours, 10 minutes between refuelling stops.
In total, the record drivers had to stop 966 times in the temporary pits set up alongside the track; refuelling and the obligatory visual check of the vehicle took around 2 minutes on average. Servicing, including the replacement of operating fluids and wear parts, was performed using the customary service interval indicator in the cockpit."
The 3 cars stopped 966 times for fuel. That is every 310 miles for each car. They have a 20 (21?) gallon tank. That is more like 16mpg, which is what one would expect.
They may go 140mph, and they may get 40mpg, but not at the same time. The article is either poorly worded, or just plain wrong in this regard.
11-14-2014, 06:07 PM
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Thanks for the clarification 
16mpg means an efficiency of around 33% (rough estimate) which still isn't too bad at full load. Many gas cars get 16mpg at 70mph lol
Normally I only bad articles on cnet... guess I have to add gizmag to the "careful" list
16mpg means an efficiency of around 33% (rough estimate) which still isn't too bad at full load. Many gas cars get 16mpg at 70mph lol
Normally I only bad articles on cnet... guess I have to add gizmag to the "careful" list
11-22-2014, 11:31 AM
#4
Driving 100K miles straight in 30 days is NOT the only measure of reliability. Driving long distances is actually "easy" for most modern engines. What I want to see is 100K miles of driving in mixed real world scenarios like stop/start in alternate frigid and hot climates. Daily starts/stops cooling the engine every night. The #1 cause of wear happens during the first few seconds of starting an engine - very little wear/stress happens to the internals when the engine is at "cruising" speed.
This article is from 2005 - in this day and age of free information - its very hard for marketing guru's to keep good, reliable information from reaching the public. The fact you are members of this forum means - you guys are on the right track and seeking good information than most people.
This article is from 2005 - in this day and age of free information - its very hard for marketing guru's to keep good, reliable information from reaching the public. The fact you are members of this forum means - you guys are on the right track and seeking good information than most people.
11-22-2014, 08:50 PM
#5
Out Of Control!!
Except at 140, you are running the engine at several times its normal cruse power.
While a good bit of wear is on cold start-up, stress degradation follows Time and Power (HP-Hrs)
While a good bit of wear is on cold start-up, stress degradation follows Time and Power (HP-Hrs)
11-25-2014, 08:35 AM
#6
Do the math:
"The vehicles were driven by three teams of six drivers, also including the former DTM contestant and current FIA Formula 1 Safety car driver Bernd Mayländer, with each driver taking the wheel for about 2 hours, 10 minutes between refuelling stops.
In total, the record drivers had to stop 966 times in the temporary pits set up alongside the track; refuelling and the obligatory visual check of the vehicle took around 2 minutes on average. Servicing, including the replacement of operating fluids and wear parts, was performed using the customary service interval indicator in the cockpit."
The 3 cars stopped 966 times for fuel. That is every 310 miles for each car. They have a 20 (21?) gallon tank. That is more like 16mpg, which is what one would expect.
They may go 140mph, and they may get 40mpg, but not at the same time. The article is either poorly worded, or just plain wrong in this regard.
"The vehicles were driven by three teams of six drivers, also including the former DTM contestant and current FIA Formula 1 Safety car driver Bernd Mayländer, with each driver taking the wheel for about 2 hours, 10 minutes between refuelling stops.
In total, the record drivers had to stop 966 times in the temporary pits set up alongside the track; refuelling and the obligatory visual check of the vehicle took around 2 minutes on average. Servicing, including the replacement of operating fluids and wear parts, was performed using the customary service interval indicator in the cockpit."
The 3 cars stopped 966 times for fuel. That is every 310 miles for each car. They have a 20 (21?) gallon tank. That is more like 16mpg, which is what one would expect.
They may go 140mph, and they may get 40mpg, but not at the same time. The article is either poorly worded, or just plain wrong in this regard.
I would rather have a car that can go 140k miles without any unscheduled repairs than buy a car that can travel 140mph for 30 days.
11-26-2014, 03:34 PM
#7
Out Of Control!!
You hit the nail on the head. This is a marketing stunt catered to those who have fat wallets and don't crunch the numbers like you do. German companies are known to brag about the extreme capabilities of their products, not so much anymore on reliability. The 80's are long gone.
I would rather have a car that can go 140k miles without any unscheduled repairs than buy a car that can travel 140mph for 30 days.
I would rather have a car that can go 140k miles without any unscheduled repairs than buy a car that can travel 140mph for 30 days.
We need to get MB and Honda in a partnership.
