I drive through hills almost everyday and since I got on some 20s wheels, the mileage has significantly dropped lol unless my speed is constant at one speed, 60-73mph is best. However, hills drink a lot of fuel.

I took a note that, going over and coming back on hills, it is about 11-13 miles total which would be about at least half a gallon, if not maybe more on the hills.

Now, if anyone knows, is it bad to put car into neutral while driving and shift it into gear when needed? Does it cause any wear on the transmission or any other parts? I don't drive aggressive, i did it once and when i put it back into gear, i let it settle for about 5 seconds at least before pressing the gas pedal.

Reason i ask is, i know auto trans is diff than manual, cuz stick shift we change gears all the time n go neutral anytime we want but is it the same with atuo trans? idk if it is bad or how bad it is to do with auto T. I read around a bit and kinda didn't see much negative about this concept.

I've tried it once or twice.

 

I was doing it on W210 for a year, when I was going long downhill with STOP sign at the end.
Mercedes advise against it.
Try if you can do it in first place. On W210 once you shifted to N, you had to come to stop before transmission would engage gear again.

 

well like i said, i did it about twice so far. I can shift to neutral or back into gear with no problems at all but i don't come to a complete stop anytime during those phases. The road is about 26 miles and its steep uphill about 8 miles and down about 5-6 miles each way. I don't come to a complete stop maybe another 12 miles after i do that.

I'm curious about it. If it is bad and how bad. what would be affected.

I mean yes that will save me about say 8-10 gallons a month? damn that's a lot lol but i don't want to sabotage anything the ride as well.

 

Aside from being illegal, cruising downhill in a high gear is proven to give better efficiency than neutral coasting. Your engine is turning over under the weight of the car, preventing gas from being consumed. Also, engine braking downhill is a better way to regulate your speed than slowly drifting up to 65 and laying on your brakes right at the bottom, where the cop is already waiting for you.

From Popular Mechanics:

 

Sorry about senior moment. The procedure of coming to stop to engage gear apply when you turn the engine off while coasting.
Shifting to N brings additional wear to transmission clutches and stress to mechanical parts. I recall that I had to rev it high before engaging the gear again at high speed.
What bryguy quoted is true, but doesn't change the fact that long downgrades can save you fuel if you don't mind risk of faster transmission wear.
This is what I've got going on neutral and trust me that display shows end of the scale as I was doing better.

 

I kinda do n don't get that concept. I mean when i go downhill on that road, due to traffic, lot of small time acceleration and braking here and there, my rpm always stay about 2,500 because a lot of gear changing. I try my best to speed up a little to change to next gear but another press on brake, im back up at 2500 rpm and sometimes it doesn't shift for awhile and it gets me frustrated lol doesn't that consume more gas when running downhill in neutral, rpm at what 1k-1.5k?

I did thought to myself that, lets say that i do save gas, wouldn't it mess with trans parts?

and Bryguy, i read that whole article, curious, how can that be same for auto and stick shift cars? How can that be bad for stick shift vehicles because if that is bad to run it in neutral downhill and shift it into gear later, then shouldn't the transmission on stick shifts wear out way sooner? I mean even on regular basis, hell it's a stick shift, u change gears like a thousand times a day. and thru the hills if u decide to change gears, in my case, you'll go thru what maybe 10-20 gear changes in about 20-30 minutes of time.

i hope that makes sense lol

 

Modern engines have computer-controlled fuel injection, what will cut the fuel completely off when coasting.
I had Audi with instant mpg display and in city traffic it would go 5-10-20 mpg then when I was coming to red light it would go to 200 mpg while in few seconds of coasting it will show "---"
What the article fails to address is that having gear engaged you are slowing the car down, so at the bottom you have to give it more gas for lost speed.
That is why I've got 99 mpg at 80 mph on steep grade regardless engine sipping fuel at 800 rpm.
You will never get that going on gear.

 

As a perfectionist i recommend
if you wanna save fuel sell the merc n buy a prius
if you wanna own a merc then fk fuel consumption n just go with the flow
and about the topic i once shifted gear to neutral while coasting in my previous car w210 and as i changed back i instantly felt a jerk so yeah its bad for the transmission as for the w211 idk i haven't n i never will try that on my car.

 

So far I drove only couple hundreds miles on it, but looks E250 BTC gets better mpg than Prius
Average city driving comes to 28 mpg and that with AC always on.
Yesterday I made 45 miles trip. 30% afternoon city traffic, 70% freeway with some traffic as well. Show 39 mpg.
Diesel here is cheaper than regural.

 

I get arround arround 12 to 13 kpl with the ac on
i only drive in the city n its fkin crowded all the time

 

i can go buy a smaller engine diesel car or prius but i see no profit off it for at least another 5-6 years. As i would spend around at least 5k to another car and for what, to save gas money...if my calcualtions are about right, with 20inch wheels and driving thru steep hills, my yearly gas expense has risen abt $500-600, buying another car for 5k...it will be years before i start seeing a profit in that lol just saying....

well when i tried neutral while doing downhill and shifted back in gear, i experienced no jerk movement or anything, it was like any other regular gear shift. Honestly there was no noise, no jerk...gear just slipped in, i waited about 3-5 secs for the gear to settle itself and gassed it, smooth as hell. Maybe w210 had issues with that whole process? not sure.

I was just curious about this whole thing, i haven't done it for awhile now, most likely won't ever again. n gas mileage, most of the times i dont really care about it, my work reimburses way more than i spend on gas for work lol

 

Bigger wheels and tires are indicative of poor fuel economy.
A ecu tune or trans tune may be what you need. Injection pulse width, cam timing a better breathing engine (intake) shift points things of that sort would maybe help some but tbh it's a double edge sword cause fuel prices fluctuate more than your mpgs.



And diesel is around the same as premium here in my area. So sometimes diesel is more beneficial. Certainly a lot easier to resell that's for dammm sure.

 

Yes i was informed that i'll get a drop in mileage. I have like drop of 2mpg, unless i drive 65-70mph, i can get mpg if i had stock wheels.

Actually i was thinking about the ECU tune but kind of put it down. I'm not too worried about the drop in mileage though.

 

Weight reduction, good tire pressure, high quality Fuel.

The Magic 3.

 

lol not sure if i wanna toss things out for weight reduction from this thing. Maybe i shall loose couple pounds lol

I haven't gotten around the tire pressure yet. Dont know how much air is needed to keep in these tires. I have em on since March.

Fuel wise, i use Costco's 91 rating. Costco fills the tank about 5-10 bucks cheaper than regular stations around here at 91 rating. So even if costco gas drops me 1 mile a gallon than Shell/76/chevron, still saves me more.

 

If you filled your gas tank with only 11 gallons vs. 21 gallons, you'd be about 62 lbs. lighter. Would that make a difference in your overall MPG! May not be that convenient having to stop more often to fill up!

 

Aside from the mechanical aspect of drive train stress shifting in and out of neutral, the important aspect is that the pump in the transmission does not circulate the fluid in neutral. It wont circulate through the radiator and causes heat to build up in the fluid which acts as a lubricant and cooling fluid for the transmission.
Auto transmissions do not do well with heat. Heat is the enemy.
For this reason alone it is not recommended to shift to neutral when coasting downhill.
The same applies when towing a vehicle with the rear wheels on the ground, it is better to remove the drive shaft.
Computer control of the fuel injection will minimize wasted fuel, but it wont save your transmission from burning up.

 

Lot of manufacturer's warnings are simple precaution as with not much need for the research - they simply don't know.
The transmission in neutral is hot subject on RV forum, where lot of cars are towed 4-down behind RV.
Years ago Saturn was advising against such procedure, but being it cheap car (at the time) some owners took their chances and towed the cars for tens of thousands miles with no ill effect.
Weight makes difference in city driving.
Once you at steady freeway speeds, even 1000 lb will bare no visible effect on mpg.
Frontal area aka roof rack will....

 

Now this is the kind of information i was seeking rather than debating which options gets best mileage lol

@geeunit are you talking about the gear pump in transmission?
I did not think of that before. That makes some sense to me. But my main question was does that going neutral and shifting into gear later while the vehicle is in motion, regardless the speed, would it have a wearing affect on the parts in the transmission?

I was talking about it with a friend and he also advised to shift neutral while coasting downhill. Yes it will save gas but how much wear would i get on the trans parts during shifting to neutral and back into gear while in motion...not sure if someone knows but i wouldn't take such a risk. I am just curious to know would there be a wear? Just tryna educate myself more about cars lol

 

Any car when you shift gear back at speed will have some jerking and stress on the drive-line.
So lubrication issues aside, you should rev the engine before reengaging the gear.