Hypermiling the RDX
05-27-2008, 10:14 PM
#1
Safety Car
Thread Starter
Hypermiling the RDX
Some reasonable techniques are sound:
A) Using side roads to avoid frequent stops and starts. Running at a more constant rpm is most efficient.
B) Reducing cruising speed by 10mph. Lower cruising rpm means fewer combustion strokes per mile.
Other hypermiling techniques are unsound and dangerous:
A) Pulse and glide or coast with forced stop. Switching the RDX ICE off (IG1) and back to Run without start (IG2) for neutral coasting leaves no steering or brake boost and runs the risk of locking the steering column.
B) Inflating the tires to 40psi, 50psi or more. While this sharpens turn-in response and increases fuel efficiency, it does so to the detriment of tire wear and overall grip due to the decreased contact patch area. The contact patch is narrower and the vehicle is riding on the center rib of the tread.
It is true that auto-crossers over-inflate but that is specifically for turn response at the expense of grip, and they don't drive home that way.
It's also true that German manufacturers advise over-inflation for the autobahn, but that is specifically for high speed temperature stability due to rapid sidewall deformation cycles, and it comes at the expense of grip and reduced load capability. Autobahn over-inflation is typically 5 to 7 psi above normal, and well within the max cold rated sidewall pressure.
Some hypermilers have stated that they see less tire wear, or make bizarre claims of no tire wear. This may be attributed to:
A) They don't know how to measure tire wear, or are looking just at the edge blocks and fail to see that the center rib is gone.
B) Some kind of eco-Green trance-like state in which -- like Lewis Carroll's White Queen -- they can believe impossible things.
A) Using side roads to avoid frequent stops and starts. Running at a more constant rpm is most efficient.
B) Reducing cruising speed by 10mph. Lower cruising rpm means fewer combustion strokes per mile.
Other hypermiling techniques are unsound and dangerous:
A) Pulse and glide or coast with forced stop. Switching the RDX ICE off (IG1) and back to Run without start (IG2) for neutral coasting leaves no steering or brake boost and runs the risk of locking the steering column.
B) Inflating the tires to 40psi, 50psi or more. While this sharpens turn-in response and increases fuel efficiency, it does so to the detriment of tire wear and overall grip due to the decreased contact patch area. The contact patch is narrower and the vehicle is riding on the center rib of the tread.
It is true that auto-crossers over-inflate but that is specifically for turn response at the expense of grip, and they don't drive home that way.
It's also true that German manufacturers advise over-inflation for the autobahn, but that is specifically for high speed temperature stability due to rapid sidewall deformation cycles, and it comes at the expense of grip and reduced load capability. Autobahn over-inflation is typically 5 to 7 psi above normal, and well within the max cold rated sidewall pressure.
Some hypermilers have stated that they see less tire wear, or make bizarre claims of no tire wear. This may be attributed to:
A) They don't know how to measure tire wear, or are looking just at the edge blocks and fail to see that the center rib is gone.
B) Some kind of eco-Green trance-like state in which -- like Lewis Carroll's White Queen -- they can believe impossible things.
05-28-2008, 09:53 PM
#3
Safety Car
Thread Starter
Originally Posted by oasis3582
Do you ACTUALLY do any of this? Please tell me no.
Originally Posted by XLR8R
Other hypermiling techniques are unsound and dangerous:
(With apologies to Dr. Phil)
05-29-2008, 07:59 PM
#5
Advanced
Gotta call you on this one. Since engine speed is directly proportional to axle speed, the same number of combustion cycles per mile regardless of speed. Aerodynamic losses are proportionally lower at lower speeds, however.
Joe
Joe
05-29-2008, 08:55 PM
#6
Safety Car
Thread Starter
Originally Posted by scudzuki
Gotta call you on this one. Since engine speed is directly proportional to axle speed, the same number of combustion cycles per mile regardless of speed. Aerodynamic losses are proportionally lower at lower speeds, however.
Joe
Joe
I should have said engine loading for a given rpm is higher at higher speed, with an accompanying increase in inlet airflow and injected fuel.
05-31-2008, 09:07 PM
#7
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Originally Posted by scudzuki
Gotta call you on this one. Since engine speed is directly proportional to axle speed, the same number of combustion cycles per mile regardless of speed. Aerodynamic losses are proportionally lower at lower speeds, however.
Joe
Joe
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05-31-2008, 10:15 PM
#8
Advanced
Of course that is true, engine speed idling in neutral is... idling. Coasting in neutral... how much of that do you get away with? My statement meant gear for gear i.e. in 3rd gear, the engine is spinning twice as fast at 50 MPH as it is at 25 MPH. I sure wouldn't mind coasting around all day. If only the roads I drive to and from work were like an Escher painting... where I could drive downhill to and from work... now that's a commute I could live with.
Joe
Joe
06-01-2008, 07:45 AM
#9
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I don't understand why someone would buy a fairly expensive performance oriented vehicle, and spend its life trying to drive it like a Prius.
If money is an issue because of gas prices, sell it and get something cheaper.
If money is an issue because of gas prices, sell it and get something cheaper.
06-01-2008, 08:45 AM
#10
Advanced
Personally, I'm mindful of keeping my foot out of the gas when I'm NOT trying to go fast in order to keep the average economy up, but I have no reservations about jamming it in sport shift mode and manu-matic-ing it through the twisties to keep 'er on the pipe (gotta keep the motor in the sweet spot for the SH-AWD to deliver its potential), or to pass some knucklehead wobbling along at 10 MPH under the speed limit.
Joe
Joe
06-01-2008, 11:35 AM
#11
Racer
Originally Posted by Fishbulb
I don't understand why someone would buy a fairly expensive performance oriented vehicle, and spend its life trying to drive it like a Prius.
If money is an issue because of gas prices, sell it and get something cheaper.
If money is an issue because of gas prices, sell it and get something cheaper.
09-07-2010, 02:46 PM
#12
Some reasonable techniques are sound:
A) Using side roads to avoid frequent stops and starts. Running at a more constant rpm is most efficient.
B) Reducing cruising speed by 10mph. Lower cruising rpm means fewer combustion strokes per mile.
Other hypermiling techniques are unsound and dangerous:
A) Pulse and glide or coast with forced stop. Switching the RDX ICE off (IG1) and back to Run without start (IG2) for neutral coasting leaves no steering or brake boost and runs the risk of locking the steering column.
B) Inflating the tires to 40psi, 50psi or more. While this sharpens turn-in response and increases fuel efficiency, it does so to the detriment of tire wear and overall grip due to the decreased contact patch area. The contact patch is narrower and the vehicle is riding on the center rib of the tread.
It is true that auto-crossers over-inflate but that is specifically for turn response at the expense of grip, and they don't drive home that way.
It's also true that German manufacturers advise over-inflation for the autobahn, but that is specifically for high speed temperature stability due to rapid sidewall deformation cycles, and it comes at the expense of grip and reduced load capability. Autobahn over-inflation is typically 5 to 7 psi above normal, and well within the max cold rated sidewall pressure.
Some hypermilers have stated that they see less tire wear, or make bizarre claims of no tire wear. This may be attributed to:
A) They don't know how to measure tire wear, or are looking just at the edge blocks and fail to see that the center rib is gone.
B) Some kind of eco-Green trance-like state in which -- like Lewis Carroll's White Queen -- they can believe impossible things.
A) Using side roads to avoid frequent stops and starts. Running at a more constant rpm is most efficient.
B) Reducing cruising speed by 10mph. Lower cruising rpm means fewer combustion strokes per mile.
Other hypermiling techniques are unsound and dangerous:
A) Pulse and glide or coast with forced stop. Switching the RDX ICE off (IG1) and back to Run without start (IG2) for neutral coasting leaves no steering or brake boost and runs the risk of locking the steering column.
B) Inflating the tires to 40psi, 50psi or more. While this sharpens turn-in response and increases fuel efficiency, it does so to the detriment of tire wear and overall grip due to the decreased contact patch area. The contact patch is narrower and the vehicle is riding on the center rib of the tread.
It is true that auto-crossers over-inflate but that is specifically for turn response at the expense of grip, and they don't drive home that way.
It's also true that German manufacturers advise over-inflation for the autobahn, but that is specifically for high speed temperature stability due to rapid sidewall deformation cycles, and it comes at the expense of grip and reduced load capability. Autobahn over-inflation is typically 5 to 7 psi above normal, and well within the max cold rated sidewall pressure.
Some hypermilers have stated that they see less tire wear, or make bizarre claims of no tire wear. This may be attributed to:
A) They don't know how to measure tire wear, or are looking just at the edge blocks and fail to see that the center rib is gone.
B) Some kind of eco-Green trance-like state in which -- like Lewis Carroll's White Queen -- they can believe impossible things.
09-07-2010, 08:23 PM
#13
Safety Car
Thread Starter
...and with that we have have been provided a rare insight -- self disclosed, no less -- into the "physics-free" zone of the Hyper-miler.
Last edited by XLR8R; 09-07-2010 at 08:28 PM.
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