[J330i]

Originally Posted by YoYo

Is there an advantage to downshifting through the gears (6-5-4-3-2-1 or 6-3-2-1 etc.) when coming to a stop from, let's say, from 60-0 mph, over simply putting the car in Neutral from 5th or 6th gear then coasting to a stop (using brakes of course)?

Do whatever you are most comfortable with...
If I feel like my right arm needs double the exercise, I downshift through the gears, otherwise, I just pop it into neutral. However, correct me if I am wrong, but doesn't downshifting while deccelerating wear out the engine more and also waste gas as the engine is still reving? I was always taught that it is cheaper to use your brake pads to slow/stop your car than to use your engine and transmission as a brake. The skilled manual driver should be able to shift into the gear of choice from neutral in a split second in case of the need of an emergency maneuver.

Just my two cents.

[Brian]

The advantage of leaving the car in gear is a slight increase in fuel economy and the ability to react more quickly if an emergency occurs.

The advantage of putting it in neutral is that you do less work while slowing down.

Neither method is going to hurt your car (well, unless you downshift horribly), so feel free to do it how you like it

[seh]

Originally Posted by Brian

The advantage of leaving the car in gear is a slight increase in fuel economy

I asked about this recently on Bimmerfest, as it runs counter to intuition. FenPhen's reply gave an explanation, with the caveat that more kinetic energy is being dissipated with the car in gear than in neutral.

Despite having read and internalized the idea almost three months ago, I still drive around in neutral most of the time. I can't break that connotation between hearing the engine revving and assuming that I'm wasting gas and making the car do more work than it needs to.

[Brian]

Originally Posted by J330i

However, correct me if I am wrong, but doesn't downshifting while deccelerating wear out the engine more and also waste gas as the engine is still reving?

It depends...

You can downshift in 3 different ways:
1) clutch in, downshift, clutch out fast
2) clutch in, downshift, clutch out slowly
3) clutch in, downshift, rev match, clutch out

As far as engine wear goes, #1 is the worst. You are mechanically forcing the engine to rev a few hundred RPM faster in a fraction of a second. That puts stress on the connecting rods and the rest of the internals. Whether or not that stress is harmful or not is up in the air. I would be willing to bet that on a strong and well-built engine you could do this day in and day out for years without ever exceeding the amount of additional stress the engine internals can handle.

#2 puts additional wear on your clutch and nothing else. I do this type of downshifting 75% of the time and have never had a clutch wear out before 100,000 miles. Of course, every car is going to be different.

#3 - no additional wear at all.

For fuel consumption, #3 is the only method in which you might use more fuel than coasting to a stop, since you have to rev the engine to match RPMs. #1 and #2 actually use less fuel than coasting to a stop. The engine controller adds the exact amount of fuel needed to keep the engine running with the load placed upon it. When coasting to a stop, the engine has zero load but must stay at idle speed. You need very little fuel to do this. But... When coasting to a stop while in gear, the engine has essentially a negative load - the wheels are turning the engine and not the other way around. You don't need any fuel at all to maintain this state, so the engine controller adds virtually none!

[Brian]

Originally Posted by seh

I asked about this recently on Bimmerfest, as it runs counter to intuition. FenPhen's reply gave an explanation, with the caveat that more kinetic energy is being dissipated with the car in gear than in neutral.

Despite having read and internalized the idea almost three months ago, I still drive around in neutral most of the time. I can't break that connotation between hearing the engine revving and assuming that I'm wasting gas and making the car do more work than it needs to.

It does seem counterintuitive at first. When I drove around in my Audi, I used to notice that when I coasted to a stop in neutral the MPG display would jump up into the 150-170mpg range, but if I coasted to a stop in gear, it would keep going past that and then once past 200mpg the display would change to ---, meaning off the charts. I used to think about it alot and after talking with friends it dawned on us that the engine controller was smarter than we gave it credit for.

[Bimmerista]

Interesting that it is predominantly in North America that people seem to skip gears.

[J330i]

Ahh...rev matching and heel-toe downshifting. An art I tried to master but my lazy mind and foot would not oblige. I tried in earnest to master the art, but only find myself executing a perfect rev match 30% of the time.

I know how you feel seh. Hearing the engine rev, when it doesn't need to be just makes me feel that the engine is working when it could be resting (at idle rpm levels).

[poldim]

Originally Posted by seh

I asked about this recently on Bimmerfest, as it runs counter to intuition. FenPhen's reply gave an explanation, with the caveat that more kinetic energy is being dissipated with the car in gear than in neutral.

Despite having read and internalized the idea almost three months ago, I still drive around in neutral most of the time. I can't break that connotation between hearing the engine revving and assuming that I'm wasting gas and making the car do more work than it needs to.

I think you said it best with

For fuel consumption, #3 is the only method in which you might use more fuel than coasting to a stop, since you have to rev the engine to match RPMs. #1 and #2 actually use less fuel than coasting to a stop. The engine controller adds the exact amount of fuel needed to keep the engine running with the load placed upon it. When coasting to a stop, the engine has zero load but must stay at idle speed. You need very little fuel to do this. But... When coasting to a stop while in gear, the engine has essentially a negative load - the wheels are turning the engine and not the other way around. You don't need any fuel at all to maintain this state, so the engine controller adds virtually none!

Although kinetic energy got you going, its the inertia from the car moving down the road, transmitted through the tranny, to the engine, is what really keeps the better fuel consumption while in gear.


My shiftting is probably 50/50 between slow clutch release and rev matching (2 and 3 from your options). I really couldnt care less about spending an extra quater per fuel tank to rev-match the engine, but at the same time, I wont be keeping the E90 for more than 4 years, so long term failure really isn't a huge problem for me.

[jbl16]

Originally Posted by davinet78

i never skip a gear
i also find that when i really want to push hard in 6th gear the car goes wonderfullly in 6th gear without having to change to 5th or 4th

At least in the 330i dropping down to 4 and gunning it, when u really want to accelerate at highway speeds makes a BIG difference, u wil find yourself doing 120-140mph in no time , I agree 95% of the time I dont need to downshift ot 4th, maybe 5th to get the rpms a little higher, but 6th is comfortable enough for passing @ 70-80mph.

[Robert A]

Why do you double clutch?

Originally Posted by petesamprs

When I need to pass, I double clutch down to 4th, pass, and shift back to 6th.
.

[AW330i]

You know while on the topic of our transmission, I think it is funny how so many people are obsessed with having short gear ratios... I for one love the fact that my 330i has a six speed that is geared like a 5 speed. Here in houston the speed limit is 60/ 65 miles per hour on almost all of the freeways which means that if I am cruising in sixth gear at 65/ 70 mph and some asshole decides to come flying up behind me and ride my ass like I am some old woman, I can downshift to third and get as far away as quickly as I could ever want to... Its amazing to me how many cars tailgate me when I try to drive the speedlimit... I have always said if you cant keep up with me than dont tailgate me it just doesnt make sense of corse my car is going to leave your pos honda in the dust. The bottom end of third gear leaves alot to be desired but 3rd gear from about 65 mph up to redline is a beast of a gear.

[noflash]

Originally Posted by AW330i

You know while on the topic of our transmission, I think it is funny how so many people are obsessed with having short gear ratios... I for one love the fact that my 330i has a six speed that is geared like a 5 speed. Here in houston the speed limit is 60/ 65 miles per hour on almost all of the freeways which means that if I am cruising in sixth gear at 65/ 70 mph and some asshole decides to come flying up behind me and ride my ass like I am some old woman, I can downshift to third and get as far away as quickly as I could ever want to... Its amazing to me how many cars tailgate me when I try to drive the speedlimit... I have always said if you cant keep up with me than dont tailgate me it just doesnt make sense of corse my car is going to leave your pos honda in the dust. The bottom end of third gear leaves alot to be desired but 3rd gear from about 65 mph up to redline is a beast of a gear.

Are you sitting in the left lane when this happens?

[ward]

Originally Posted by noflash

Are you sitting in the left lane when this happens?

exactly my thoughts on the issue


driving the limit is pretty much an a-hole maneuver unless you're in traffic or in the far right lane

[shimshimhada]

Originally Posted by noflash

Are you sitting in the left lane when this happens?

I was going to post the same thing, but I thought it'd be almost rude to ask

[ward]

who tailgates when they could just go around???? I bet he is in the fast lane


(don't get me wrong though, I like to stir people up too sometimes...)

[AW330i]

No I am allways on the far right when I drive the speed limit... For being such a young driver I have seen a lot of shit behind the wheel, I used to do hot laps around the beltway at 130-140 with my friends for shits, we would weave through cars and use shoulders to pass people at double the speed limit. I have watched friends seriously injured in terrible accidents and while it took a lot to get me to calm down behind the wheel including some pretty bad tickets I now try not to speed as much as I used to... I am trying to keep the E90 as perfect as I possibly can and that definatly involves much safer driving habits. I am still young and I do still speed. I am not perfect, but I have realized now that there is plenty of time in a day for me to go where ever it is that I want and that I dont have to get there in record time. Here people tailgate everywhere not just in the left lane but in all lanes especially if there is any traffic whatsoever... People would much rather "push" you out of there way than have to go around you.

[poldim]

I like to tap the brakes just so that the lights turn on. I always hate being behind nice cars, their brake lights are too bright. If that doesnt work, I use the brake until they get the point.

[dude007]

Originally Posted by poldim

I like to tap the brakes just so that the lights turn on. I always hate being behind nice cars, their brake lights are too bright. If that doesnt work, I use the brake until they get the point.

Yep, I use the same strategy, if it doesn't work I slow down then accelerate to shake them off, if they come too close again - I slow down again. About 99% of people get it: stay too close on my tail and he will be driving even slower... However, most of the time brake lights are sufficient.

[vladinecko]

yeah, they put the gear/position indicator into automatics but not manuals where it would make more sense. i don't get it.

i don't find any of the gears useless. once i hit 60mph, i shift to 6 right away to keep the rpms around 2-2.5k and find it unnecessary to go all the down to 4 or 3 just to pass someone because at that speed and on a flat surface, 5th gear gives me plenty of power to pass someone pretty fast. why rev the engine up if you really don't have to?

[jhbodle]

Originally Posted by dude007

Yep, I use the same strategy, if it doesn't work I slow down then accelerate to shake them off, if they come too close again - I slow down again. About 99% of people get it: stay too close on my tail and he will be driving even slower... However, most of the time brake lights are sufficient.

I keep thinking of doing this, but I keep worrying that the bloke behind wont react quickly enough and plow into the back of me. If they are tailing you that closely, their driving skills (and quite possibly their intelligence) obviously leave a lot to be desired. Has anyone ever been hit by doing this? I'm curious...

[poldim]

Originally Posted by jhbodle

I keep thinking of doing this, but I keep worrying that the bloke behind wont react quickly enough and plow into the back of me. If they are tailing you that closely, their driving skills (and quite possibly their intelligence) obviously leave a lot to be desired. Has anyone ever been hit by doing this? I'm curious...

Im sure they have, but the damage will (should) be very limited since its only a 5 to 10 mph differential.
At that point, when you stop, calmly call the cops and tell them that you have been rear ended by an aggressive driver. Call a lawyer, a good one, and enjoy the time off from work and the time you will spend at the chiropracter because your neck back and knees hurt. Then enjoy a big settlement thats worthy of a down payment for the E90 M3.

[jhbodle]

Originally Posted by poldim

Im sure they have, but the damage will (should) be very limited since its only a 5 to 10 mph differential.
At that point, when you stop, calmly call the cops and tell them that you have been rear ended by an aggressive driver. Call a lawyer, a good one, and enjoy the time off from work and the time you will spend at the chiropracter because your neck back and knees hurt. Then enjoy a big settlement thats worthy of a down payment for the E90 M3.