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  #1  
Old 03-08-2001, 01:22 PM
Mervyn's Avatar
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Hi everyone, this question has been on my mind the day I bought my first automatic transmission, a 1983 W126 (280SEL). I have always wondered if there is an ideal way to floor the gas pedal, especially from stationary.

Should I gently depress the pedal allowing the car to pick up speed, and all this while keeping the fuel economy needle below the half-mark? Or should I floor the pedal much more and letting the fuel economy needle hit the max?

Or is the fuel economy gauge an indicator at all in determining how fast, how much we step on the gas pedal?

I heard that the car will consume more fuel if we allow the automatic car to drag, so therefore it is a better option to pick the car up as soon as possible and get it into a cruising gear.

My main objective for asking this question is more geared towards fuel economy.

And since I'm on this, another question is: should I leave the gear in "Drive"(D), "Neutral"(N) or "Parked"(P) during traffic stops? Is it true that leaving it in Neutral will eventually harm the auto transmission?

Thanks for all input in advance!

Mervyn
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  #2  
Old 03-08-2001, 02:02 PM
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I can answer your 2nd question, and I'll attempt to answer your second one also.
In a book that I have, DRIVE IT FOREVER, it states that whenever you're at a stoplight or whatever for more than a minute, you should put the car into Neutral. It gives the transmission a breather, kind of like a break.
As for the 1st question on how to floor it... If you are flooring it for economy, then that is an oxymoron. But I suppose there is a way to accelerate that is better mpg (lightly?), somebody else help me out on this one?
But if you are flooring to FLOOR IT and GO, then instead of just JAMMING on the gas pedal, do as follows; I think it puts less strain on the drive train to do it this way...
At a stop light, it turns green, slowly push the pedal all the way down (but still while keeping it in first gear), some timing is involved and it might take getting used to. I slowly floor it, but all the while the auto trans is still in first. And by the time my foot is at the floor, the car is redlining and shifting to second. Anyone disagree that is a bad way to floor it?
I hope this helps you out. Sorry, it's a bit confusing.

[Edited by Hottee18m on 03-08-2001 at 01:21 PM]
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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #3  
Old 03-08-2001, 04:51 PM
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Is the reason you are flooring the pedal because you are leaving from a stop light, or are you in a passing situation that requires immediate power? If you require an immediate surge of power, than there would be a certain amount of urgency? Soooooooo you would want to pass as quickly and safely as possible therby depressing the accelerator in direct proportion to your need of ungency!
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Old 03-08-2001, 04:54 PM
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i believe its also good to let off the petal before it shifts. that puts less strain on the trans. by the way, i always put my cars in neutral at stoplights by habit. i thought it wasn't good for it. i guess i was doing the right thing after all.
adam
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PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320

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  #5  
Old 03-08-2001, 05:55 PM
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Is there any proof that it is better on the transmission to let off the gas a little when the trans shifts? What does everyone think about that? I think about that a lof ot the time, but only do it sometimes.
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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #6  
Old 03-08-2001, 07:07 PM
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If you need emergency power for passing or whatever, punch it. Otherwise use common sense and good judgement. Anytime you apply max power from a standstill, you are applying max stress to the drivetrain. Drop shifting also falls in the max stress category. You have a reliable unit in your car. If you are driving with the pedal to the floor and you decide to unload the drivetrain by getting off the gas as it shifts, be sure you get the timing of this move correct, or you may end up putting a large deceleration load on the drivetrain if you don't get it right. Just use common sense and you will be fine.
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  #7  
Old 03-08-2001, 10:39 PM
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Funny, I have never driven according to the Economy meter.

I drive casually, i.e. gradual acceleration and gentle braking, when in a leisure mode, and not in any sort of hurry. Average speed, 0-100 km/p - approx. 13 secs, and pedal is depressed gradually.

When in an extreme hurry - which is seldom, I floor the pedal to get max revs, and shoot from 0 - 100 km/p - approx. 7 secs within, and thats when the gear changes at higher revs.

For max. fuel, I would use the casual drive mode.
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  #8  
Old 03-09-2001, 01:50 AM
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I guess I was a lil overengrossed in the fuel economy gauge.Somehow that needle seems to want to dictate my right foot.

Ok, so I presume that it is not too wise an idea getting the foot too much off the gas pedal when the trans shifts, reason being that the deceleration puts a lot of load on the trans. Right? Makes lots of sense to me though, thanks.

Well, I drive casually most of the time too, but I just had this nagging thought that if there IS a better way of controlling the gas pedal, maybe I ought to know it. So at least I can justify to myself why I do it this way.

And err.....any more views on what gear to engage in during stoplights?

Cheers,
Mervyn
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  #9  
Old 03-09-2001, 03:51 AM
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hi Merv - at longgggggg (added emphasis) stop lights, I would step into N, and watch the idle rev. its superb when the cars so well tuned and I could hardly feel the tremor of the engine. If I sense any vibration, unless its caused by rising heat in our tropics, then I might just pay more attention to the idling.

If its short, or I dont know when coz its the first time I was at the light stop, then I'm prepared at D as it has no effect whether its on N or D, and the pressure on the brake pads aint that great either. Perhaps others might have their own views.

This might draw some response from people who prefer manual cars where they're sure to dis-engage the clutch to neutral.

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  #10  
Old 03-09-2001, 11:44 AM
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Since there are many *correct* answers to your question, I'll add my $0.2 here also. There's probably as many potential answers as the Braking question. I've found that in order to get full seat-of-the-pants power in an MB, you need to push the pedal fully to the floor. According to someone else on the list, there is a switch that downshifts the tranny. Have fun, be safe, but drive it like you stole it!
Gary
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  #11  
Old 03-10-2001, 12:49 PM
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Idling in gear won't "hurt" a transmission. The "slip" of the torque converter WILL heat up the transmission fluid, but this is normal. All cars have a transmission fluid cooler in the radiator, and sometimes an additional external cooler for heavy-duty applications like towing. Unless your torque converter has a "lockup" feature it's always slipping during normal driving and that's why automatics are less efficient that manuals.

Go ahead and smack that right pedal down anyway you want. As the airflow in the engine picks up the EFI will add gasoline as required. Yes, carburetors will too. The amount of power you ask for with your right foot won't damage the valves, or any other engine component at any rpm as long as it stays within limits. Ditto for the transmission, no need to back off, just plant that foot. Some high-output engines have a fuel cut-off which is engaged by the transmission during up-shifting to unload the drivetrain, but that's more for a F1 car than yours.

Each manufacturer's testing is a lot more severe than your driving, and its normal, un-modified power output allows it to be driven in any mode you choose between these limits. Remember that these limits include correct tire pressure, tread depth and size, as well as engine temperature, oil level and pressure. If you're making a TON of power for a long time, keep an eye on the gauges. Oh yeah, also keep an eye out for speed limits, cornering traction and radar too!

You will use fuel, brake pads, rotors, tires, clutch discs, and other "consumables" at faster rate but there won't be metal-bending damage.

Keep up the regular maintenance, go out and enjoy it!




BCingU, Jim
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  #12  
Old 03-10-2001, 08:11 PM
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Mervyn, it is pleasing to know of another 280SEL driver. Are you located in the US? I have yet to see a 280SEL save the one I drive.
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  #13  
Old 03-10-2001, 08:38 PM
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JIM H

Well that's good to know! I do floor it quite a bit. What about long terms??
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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #14  
Old 03-10-2001, 10:13 PM
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Location: Near Williamsburg, Virginia
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I just drive the snot out of my cars. I figure if I break something I'll fix it. I've got over a million miles on the two diesels and 2 gas cars I'm driving and I've never rebuilt a transmission. We have a 5-speed in a turbo diesel ... 2nd is good for a max of 40 mph. My wife was driving and heading up a 7000 ft climb outside LA and I suggested she down shift form 5th to 4th. She downshifted from from 5th to 2nd (missed the gate) and at 60 mph laid a patch as the rear wheels slowed. 200,000 miles have passed and the tranny still doesn't show any ill effect.
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  #15  
Old 03-11-2001, 12:41 AM
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Regular maintenance and constant vigilance is very necessary, even though ME engines AND tranny are known to be hardy creatures.

Just drive as you please, and try as much to be a law-abiding MB driver ...
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