Anybody else see the "hypermiling" segment on CNN?

[MinivanMauler]

Anybody else think that some of these techniques:

(1) Are not particularly good for the longevity of your engine, particularly the practice of shutting down and restarting the engine in traffic.

(2) Some of them may outright get you killed.

You can read about it here: http://www.hypermiling.com/

 

[MrCritical]

There's something seriously wrong if he's only getting 40mpg in all that city driving with a Prius.

 

[John_K]

If you get killed, you will use significantly less gas.

John

 

[terminaldegree]

I love the one where the "expert" shuts off the car while rolling, before applying the brake to stop at a traffic light. He calls it an "advanced technique"! Effectively disabling the ABS and limiting the efficacy of the brake booster sounds like an awesome idea...

From the time he cold-started his Honda to the time he was in gear and moving was about .5 seconds max, and I think he was also advocating downshifting to 1st gear on an automatic for engine braking at some point (potential gas savings vs. using the brake = huh?) with the reporter's SUV.

A lot of silly and unwise advice to cloud a trend that has good intentions, IMO. FWIW, I do shut my car off at particularly long red lights or if I'm stuck with a train crossing, but after only 10 seconds... no way!

 

[Steve S]

If it is on T.V. it has to be the truth!

 

[Benzadmiral]

Turning the car off and on so often can't be good for the starter. I've been trying out the shift-to-neutral-at-stoplights technique. I'd be nervous to try it if the car weren't standing still, though. The column lever on the Buick is too easy to shift to reverse by mistake. But I've always been one to coast (with engine on, foot off gas) toward red lights.

We'll see how the shift-to-neutral thing works out over a couple of fillup periods.

 

[Steve S]

Shifting to n can't be good Extra cycles with an auto trans. I don't turn off my engine .

 

[Gary Allan]

I have no issue with turning off the engine in grid lock. There's little productive use of the engine running unless it's 85F+ with higher humidity.

What I attempt to do is smooth out the "slinky" by going one speed in one gear and not using brakes if at all possible. Usually some flaming flamer takes that as an opportunity to commit their impatience in the gap that I form. Traffic behind me usually gets it (they have little choice, but don't appear to get anxious either - they're not passing me and not honking horns).

 

[MrCritical]

If you don't have a hybrid you won't be turning off the engine in stalled traffic here-typical mid 90's temp with 80+% humidity.

 

[mechtech2]

In Germany, and other places, cars HAVE to turn off at stoplights when the traffic light tells them to.
They have special systems on the cars to facilitate this.
Overall, it is not a bad idea.

 

[byez]

Would shifting to N on an auto really have an effect on longevity or would the difference be negligible?

Does it really save gas shifting to N at stoplights?

 

[Gary Allan]

It may or may not save fuel. It will reduce the heat generated by your tc impeller spinning fluid against a stationary turbine. It will unload the engine ..but it may just spin up to soak up the same fuel when unloaded.

 

[Shannow]

Originally Posted By: byez
Would shifting to N on an auto really have an effect on longevity or would the difference be negligible?

Does it really save gas shifting to N at stoplights?


The oil pump is driven by the outside (rotating element) of the torque converter, otherwise there'd be no pressure to engage drive.

When in drive, the engine is pumping oil around the torque converter so I believe that neutral will save some fuel in a current engine (30 year old ones always had a high idle to allow the drag in drive).

Auto- engine off down hill, I beleive is in some increased danger. The old powerglides had two pumps. One on output shaft, one on input shaft...they could be push started sort of...but also self lubricated when towed or coasting.

 

[Schmoe]

I've wonder about the shifting to N when you know you can. Is it best to put it back in D when you come to a complete stop? Does it hurt the AT if you put it in D when your still moving?

 

[PT1]

I have increased my MPG by refusing to stop at stop signs or red lights ever......

 

[Gary Allan]

Originally Posted By: Schmoe
I've wonder about the shifting to N when you know you can. Is it best to put it back in D when you come to a complete stop? Does it hurt the AT if you put it in D when your still moving?


I can't think of any obvious reasons why you wouldn't. If you're a "rollah-coastah-playah" ..it's mandatory. I had a sticking throttle position valve pre-Auto-Rx. Sometimes I'd have to put it in N and then back into D to avoid going 65+mph to get in 3rd. This was usually done in motion. When my daughter encountered it (it wasn't a full time condition - rather rare) I advised to to come to a stop just due to her lack of driving savvy in multitasking. She's not a "driver". She's a passenger at the helm.

 

[Cutehumor]

Originally Posted By: PT1
I have increased my MPG by refusing to stop at stop signs or red lights ever......

Yeah, I just don't make complete stops at stop signs and I run red lights so I don't have to waste gas

 

[PT1]

Originally Posted By: Cutehumor
Originally Posted By: PT1
I have increased my MPG by refusing to stop at stop signs or red lights ever......

Yeah, I just don't make complete stops at stop signs and I run red lights so I don't have to waste gas

LOL, I like the guy pushing his car. What a freak..why not just get a bicycle or a Prius? Wait until he gets smacked from behind from someone who isn't hypermiling. It makes some sense to coast and certainly drive slower if you wish to improve mileage. But this shuting the car off and coasting in neutral is going to cause major accidents by those incapable of handling a vehicle or those behind them not realizing there is a hypermiling idiot in front of them who may jump out and start pushing his car. They should be required to paint their car bright orange with white reflector tape big warning stickers. Sheesh!

 

[badtlc]

Originally Posted By: Gary Allan
It may or may not save fuel. It will reduce the heat generated by your tc impeller spinning fluid against a stationary turbine. It will unload the engine ..but it may just spin up to soak up the same fuel when unloaded.


You are correct except for the last part. It does save fuel. It takes gas to create that heat dissipated in the torque converter.

I have begun doing this and my MPGs have gone up about about 2mpg for my city driving. I went from 29mpg to 31mpg. For my car, though, it idles at the same RPM whether in D or N, but in N, it isn't fighting the torque converter.

 

[PT1]

Originally Posted By: badtlc
Originally Posted By: Gary Allan
It may or may not save fuel. It will reduce the heat generated by your tc impeller spinning fluid against a stationary turbine. It will unload the engine ..but it may just spin up to soak up the same fuel when unloaded.


You are correct except for the last part. It does save fuel. It takes gas to create that heat dissipated in the torque converter.

I have begun doing this and my MPGs have gone up about about 2mpg for my city driving. I went from 29mpg to 31mpg. For my car, though, it idles at the same RPM whether in D or N, but in N, it isn't fighting the torque converter.


Sure it will work, but now you are cycling the transmission much more than normal so your MPT (miles per transmission) will go way down. SO how far do you have to drive getting an extra 2 mpg to make up for the cost of a new trans. Reminds me of my neighbor who bought a Lexus RX400 Hybrid and paid $9,000 more tha I did with my RX330 for the same vehicle. He has to drive an additional 51,750 miles to break even with my fuel cost for the cost of his "hybrid". Then at 100-150k he has to pay an addiional $7,000 for a new battery pack.Which is an additional 41,000 miles to break even on that one.

So if you are getting 31mpg and gas costs $4.00/gal it is costing you $.13 per mile for fuel. You are saving $.26 per gallon by shifting into neutral and back to drive. Assuming a transmission rebuild/repair is $3,000. You need to get about 23,000 miles MORE than the average life of an average transmission in you vehicle model to break even by doing this shifting ordeal.

Just a thought...