XeroK00L

...says me.

I read a few months ago that one of the main reasons cars with manual trannies typically get better gas mileage than with automatics is because people have to place gears in neutral at stoplights, keeping the RPMs low and thereby saving fuel. I thought to myself right there and then--who says I can't do the same on my ES300 with automatics?

So I did, switching the gear to neutral, at stoplights, from stop signs to stop signs right after I've accelerated enough, when I anticipate a slow-down either due to the traffic ahead or an exit, and basically whenever my right foot is not on the gas pedal.

By practicing this principle religiously, I've seen a clear 2mpg increase in my average gas mileage from around 17mpg to 19mpg.

Now the question is, will this frequent gear switching wear off my tranny more quickly, and if so, will my gas saving justify the cost of a shortened tranny life? Opinions, anyone?

King7Two

My dad does the same thing in his 528......
At first it was kind of annoying to me.......I mean ....whats the point?

But after I thought about it........I've actually found myself doing the same thing. ( he must have subliminally planted it in me I guess)
I rarely do it though......and I have too much of a heavy foot to see any mileage increases.

Guess I just wanted to say that....well, your not alone.

Koma

iTrader: (3)

I find this somewhat problematic.
1. This would only theoretically be good if you're coming to a full stop.
2. Neutral tends to be a higher idle than drive at stop
3. It's like doing small N-bombs on your tranny because the gears are still spinning when you put it back into drive if you haven't stopped completely. Think of it this way, if you put the car into neutral at 2k RPM and re-engage it at 1k RPM the gears are still spinning at 2k (est.) and the engine is spinning at 1k when you re-engage it. So it has to catch hard onto the gears.

This is not science by the way. It's just me making a hypothesis.

GFerg

Well what if you rev match before throwing it back in Drive?? I do that with my manual car if I end up coasting but need to get back in a gear while at higher speeds.

Yea, I understand the logic, I actually do that as well(on my manual car though, dont really practice it on the autos). But I havent noticed a significant difference. Maybe 1mpg.

Falcon LS

I have a habit of shifting into neutral before I brake to come to a stop. Then again I hate keeping my foot on the brake at traffic lights.

cal_alum98

YMMV

http://www.cartalk.com/content/colum...ctober/04.html

As I understand, the main reason why a manual tranny gets better mileage is because there is a solid connection between the engine and the wheels, whereas an automatic tranny employs a fluid connection a la torque converter.

Koma

iTrader: (3)

Can someone tell me how you "rev match" in an auto or a manual?
Never really understood that logic. Supposedly you can bypass the clutch if you throw the shifter at the right time (RPM).

mmarshall

You understand correctly. Modern automatics, however, have a lock-up mechanism in at least the top gear...and sometimes lower ones as well.....that eliminates the slippage and added RPM's from the fluid torque converter. The lock-up, of course, disengages as the car slows and comes to a stop......otherwise the engine would stall.

bitkahuna

iTrader: (20)

I suspect you're getting better mileage because you're just driving slower overall. As an experiment you might just try driving without shifting into neutral but also without abrupt acceleration or decelleration. You might get the same 'increase'.

4TehNguyen

iTrader: (1)

i dont think the transmission would still be spinning if the car is in neutral, the tranny isnt connected and getting no power from the engine. As for rev matching I would think the synchros in a tranny took care of this

Koma

iTrader: (3)

Well wouldn't you just be disconnecting the engine from the tranny when putting it in neutral? So the tranny wouldn't just stop dead, right?

manila_boy

i agree to this, it really saves gas specially when ur in the fwys-just watch out for those RPMs! on the other hand making the car put to stop it eats a lot of ur brake pads, i guess the logic here is when u put ur car into neutral (heading into a near stop) when u pull the brakes it is the only thing that makes the car slow down and make it stop as for having it or leaving it into D or in the gear when ur about to stop the engine/trans helps the car to slow down because it automatically shifts into lower gear when ur slowing down-sort of like doing an engine brake. i'm me don't know if i explained it correctly. i've been doing this ever since (on manual/auto cars) and every time i tell it to someone they don't beleive me! ow well...

JZA80MHU38

Didn't the car lost all the traction when you put it in neutral? Will the VSC/VDIM/TRAC work when the car is in neutral?

manila_boy

hmmm... good point

MGS4

I almost always shift to N at stoplight. Most of my friends do this as well.