Carbon measured as a part of EPA mpg Test
#31
07-14-2005, 10:47 AM
Re: Carbon measured as a part of EPA mpg Test
I say leave the tests AS-IS. That way we can compare historically to see how improved vehicles are from previous models.
BUT also include a third number, the average actual fuel economy in a new test that is based on a sample of cars driven by commuters, similar to what is collected as data here.
Then people will realize both that people drive like idiots on the average, and that the car is capable of much better.
BUT also include a third number, the average actual fuel economy in a new test that is based on a sample of cars driven by commuters, similar to what is collected as data here.
Then people will realize both that people drive like idiots on the average, and that the car is capable of much better.
#32
07-14-2005, 11:53 AM
Re: Carbon measured as a part of EPA mpg Test
Hi Lars-ss:
___I am not trying to gang up on you at all. All EricGo and I am saying is that if you place a Prius II or Escape HEV under the exact same circumstances as the EPA test cycles, they will achieve very similar results as the test subjects (Prius II and Escape HEV) running that treadmill minus the correction factor. It doesn’t matter about a hypermiler’s setup or techniques, it only matters what the test cycles acceleration rates, deceleration rates, stop/idle times, and top speeds. With my own personal experience, I know why the Prius II can do what it does in that test cycle and there is no denying its capabilities if you were to drive the Prius II similar to the tests cycles(s) parameters. If you run a Toyota Sequoia through that same test cycle, it to will achieve very similar results as that of the test subject (tested Toyota Sequoia) minus the correction factors as well. Totally lousy in the case of the Sequoia mind you but it will achieve very similar results as what the EPA cycle estimates it should receive.
___Accessory use: Here is where a Hybrid has an extreme disadvantage in the real world. I am considering the Prius II here because that is the EV capable hybrid we are mostly talking about. It has a relatively weak 1.5 L Echo sized block running ~ 76 HP/82 Ft.-Lb’s of torque. What happens when you start up A/C in one? I know it is electric and has decent efficiency but it is still an estimated (my guess???) 2 HP draw on an ICE that was designed for the utmost FE when driven in an almost no-load condition at cruise. That 76 HP at peak or maybe 17 - 20 HP or less at no-load cruise is now saddled with a very uncomfortable for it, additional 2 HP load. That Prius II’s ICE gets hammered hard and so does its FE! Now let’s consider the Sequoia’s 282 HP/325 Ft.-Lb’s of torque. What kind of FE hit do you think adding a 3 - 4 HP A/C load to it would do to its FE? At a no-load cruise, it probably has upwards of maybe 60 HP on tap. I am completely guessing here as well. Anyway, can you see the differences? Even our MDX sees maybe a 3 - 4 mpg hit when its being hypermiled between A/C on and A/C off. The Insight would see as much as a 30 - 40 mpg hit while being hypermiled! I believe that hit is mostly due to the smallish ICE and the way its run for max FE at close to the magic no load cruise/max FE condition.
___Emissions: It doesn’t matter of a hybrid could travel 90% of the EPA test cycle in EV or 0% of a test cycle in EV. If the pack is left in a similar state at the end as it was in the beginning, the overall ICE run times and emissions are what they are. When the ICE runs, it emits. If it charges the pack to the same SoC as it was at the beginning of the test and propels the vehicle through the test course in the manner the tests dictate, the bag emissions will show what its emissions are. There is no magic here that I see. It simply shows that the ICE or system for that matter no matter how efficient or not generates a given amount of HC’s, NOx, CO, CO2, and PM through that test cycle. The measurement accounts for it and you have both the FE and the Emissions for comparison against other vehicles in the same test no matter if that test is real world reality based or not.
___Good Luck
___Wayne R. Gerdes
___Waynegerdes@earthlink.net
___I am not trying to gang up on you at all. All EricGo and I am saying is that if you place a Prius II or Escape HEV under the exact same circumstances as the EPA test cycles, they will achieve very similar results as the test subjects (Prius II and Escape HEV) running that treadmill minus the correction factor. It doesn’t matter about a hypermiler’s setup or techniques, it only matters what the test cycles acceleration rates, deceleration rates, stop/idle times, and top speeds. With my own personal experience, I know why the Prius II can do what it does in that test cycle and there is no denying its capabilities if you were to drive the Prius II similar to the tests cycles(s) parameters. If you run a Toyota Sequoia through that same test cycle, it to will achieve very similar results as that of the test subject (tested Toyota Sequoia) minus the correction factors as well. Totally lousy in the case of the Sequoia mind you but it will achieve very similar results as what the EPA cycle estimates it should receive.
___Accessory use: Here is where a Hybrid has an extreme disadvantage in the real world. I am considering the Prius II here because that is the EV capable hybrid we are mostly talking about. It has a relatively weak 1.5 L Echo sized block running ~ 76 HP/82 Ft.-Lb’s of torque. What happens when you start up A/C in one? I know it is electric and has decent efficiency but it is still an estimated (my guess???) 2 HP draw on an ICE that was designed for the utmost FE when driven in an almost no-load condition at cruise. That 76 HP at peak or maybe 17 - 20 HP or less at no-load cruise is now saddled with a very uncomfortable for it, additional 2 HP load. That Prius II’s ICE gets hammered hard and so does its FE! Now let’s consider the Sequoia’s 282 HP/325 Ft.-Lb’s of torque. What kind of FE hit do you think adding a 3 - 4 HP A/C load to it would do to its FE? At a no-load cruise, it probably has upwards of maybe 60 HP on tap. I am completely guessing here as well. Anyway, can you see the differences? Even our MDX sees maybe a 3 - 4 mpg hit when its being hypermiled between A/C on and A/C off. The Insight would see as much as a 30 - 40 mpg hit while being hypermiled! I believe that hit is mostly due to the smallish ICE and the way its run for max FE at close to the magic no load cruise/max FE condition.
___Emissions: It doesn’t matter of a hybrid could travel 90% of the EPA test cycle in EV or 0% of a test cycle in EV. If the pack is left in a similar state at the end as it was in the beginning, the overall ICE run times and emissions are what they are. When the ICE runs, it emits. If it charges the pack to the same SoC as it was at the beginning of the test and propels the vehicle through the test course in the manner the tests dictate, the bag emissions will show what its emissions are. There is no magic here that I see. It simply shows that the ICE or system for that matter no matter how efficient or not generates a given amount of HC’s, NOx, CO, CO2, and PM through that test cycle. The measurement accounts for it and you have both the FE and the Emissions for comparison against other vehicles in the same test no matter if that test is real world reality based or not.
___Good Luck
___Wayne R. Gerdes
___Waynegerdes@earthlink.net
#33
07-14-2005, 02:45 PM
Re: Carbon measured as a part of EPA mpg Test
It sounds like the next area where we need to see technological advancements is with automotive A/C systems. It's too bad they don't have ratings like the SEER ratings they put on home A/C units and heatpumps. That would make it interesting to compare the efficiency of the climate control from one vehicle to the next, especially for folks that live in hot/humid climates and use the A/C at least half or more of the year.
#34
07-14-2005, 03:19 PM
Re: Carbon measured as a part of EPA mpg Test
Hi Wayne:
I understand the 'AC hit' differently. Not a case of stressing out the engine to where it does not want to go, but rather a proportionality hit:
(made up but hopefully ballpark numbers):
2 kW AC added to the engine load .. both vehicles cruising at 35 mph.
Prius jumps from 4 kW to 6 kW
Clunker jumps from 12 kW to 14 kW
Prius takes a 50% mpg hit
Clunker takes a 16% mpg hit
Better engine in the clunker ? nah. Just equally onerous AC obscuring the differences.
I understand the 'AC hit' differently. Not a case of stressing out the engine to where it does not want to go, but rather a proportionality hit:
(made up but hopefully ballpark numbers):
2 kW AC added to the engine load .. both vehicles cruising at 35 mph.
Prius jumps from 4 kW to 6 kW
Clunker jumps from 12 kW to 14 kW
Prius takes a 50% mpg hit
Clunker takes a 16% mpg hit
Better engine in the clunker ? nah. Just equally onerous AC obscuring the differences.
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