Auto driving tips
Discussion
Hi,
At the weekend I bought my first ever automatic.
I've driven autos before, but only for short periods when other people are paying for the fuel, so I never really considered the details.
The car is a Rover 75 diesel (don't worry, I have a valid reason!) which uses an old fashioned five speed torque converter rather than a dual clutch box or AMT.
I was wondering if anyone had any tips on using an auto 'box - particularly where economy is concerned?
I've got into the habit of sticking the car in neutral at the traffic lights, but I've heard conflicting reports of whether or not the JATCO gearbox is clever enough to do that automatically when you come to a standstill.
Similarly, I was wondering when the transmission losses are at their highest? Is it more efficient to accelerate rapidly and then ease off or spend a longer amount of time getting up to speed (bearing in mind this is a diesel with no throttling during normal running...)
Anyway, I'm all ears.
Chris
At the weekend I bought my first ever automatic.
I've driven autos before, but only for short periods when other people are paying for the fuel, so I never really considered the details.
The car is a Rover 75 diesel (don't worry, I have a valid reason!) which uses an old fashioned five speed torque converter rather than a dual clutch box or AMT.
I was wondering if anyone had any tips on using an auto 'box - particularly where economy is concerned?
I've got into the habit of sticking the car in neutral at the traffic lights, but I've heard conflicting reports of whether or not the JATCO gearbox is clever enough to do that automatically when you come to a standstill.
Similarly, I was wondering when the transmission losses are at their highest? Is it more efficient to accelerate rapidly and then ease off or spend a longer amount of time getting up to speed (bearing in mind this is a diesel with no throttling during normal running...)
Anyway, I'm all ears.
Chris
The first thing I would do having had the same engine in a ZT manual is remove the EGR and give it a good clean. It will be full of Gunk. I did this a couple of times before drilling out the internals and blanking the T-piece and filling the bleed with Araldite before reattaching the small hose 3-4mm. This seemed to keep the mileage at its optimum without a slow drop to lower mpg.
The auto box can be raised a cog a little earlier by feathering the throttle back, that said I never noticed much improvement. The auto was on a 2.5 75 connie I owned before the CDTi ZT. Over on the 75/ZT forum there is a lad Big Russ who will load a 160 bhp map for little money that will see the car go better with no change in mpg
Steve
The auto box can be raised a cog a little earlier by feathering the throttle back, that said I never noticed much improvement. The auto was on a 2.5 75 connie I owned before the CDTi ZT. Over on the 75/ZT forum there is a lad Big Russ who will load a 160 bhp map for little money that will see the car go better with no change in mpg
Steve
Edited by stevemiller on Sunday 3rd February 09:49
My take on this (having owned similar cars with manual, torque converter, and DSG transmission). I'm not an expert, though - feel free to disagree with me.
When stopped (e.g. at traffic lights):-
If it's a conventional torque converter transmission, apply the handbrake and leave it in "Drive". All the brakes/clutches in the transmission are fully engaged, no moving parts are rubbing together, and the only friction is the transmission fluid churning around in the torque converter. On the other hand, shifting from "Drive" to "Neutral" (and back again) will cause some of those transmission brakes/clutches to disengage and re-engage - it's "lumpier" and causes (probably insignificant) wear to the friction surfaces.
If it's a DSG (or whatever the equivalent name is) box, you should consider selecting neutral if you're stopped for more than a few seconds. If you don't, the mechatronics will try to emulate a slushbox by keeping (one of) the clutch(es) at biting point - causing (probably significant) wear to the friction surfaces.
If it's a manual box, then the "normal" rules apply. Clutch in and hold it on the brake for a short stop; into neutral and handbrake on for a longer stop. Don't try to "hold" it on the clutch (unless you want an expensive bill for clutch replacement).
When stopped (e.g. at traffic lights):-
If it's a conventional torque converter transmission, apply the handbrake and leave it in "Drive". All the brakes/clutches in the transmission are fully engaged, no moving parts are rubbing together, and the only friction is the transmission fluid churning around in the torque converter. On the other hand, shifting from "Drive" to "Neutral" (and back again) will cause some of those transmission brakes/clutches to disengage and re-engage - it's "lumpier" and causes (probably insignificant) wear to the friction surfaces.
If it's a DSG (or whatever the equivalent name is) box, you should consider selecting neutral if you're stopped for more than a few seconds. If you don't, the mechatronics will try to emulate a slushbox by keeping (one of) the clutch(es) at biting point - causing (probably significant) wear to the friction surfaces.
If it's a manual box, then the "normal" rules apply. Clutch in and hold it on the brake for a short stop; into neutral and handbrake on for a longer stop. Don't try to "hold" it on the clutch (unless you want an expensive bill for clutch replacement).
Chris71 said:
I was wondering if anyone had any tips on using an auto 'box - particularly where economy is concerned?
Based on experience with a Merc diesel auto:Try not to stop - getting a diesel auto moving seems to take a lot of effort. In the same vein, without being ridiculous about it, try and carry as much speed as possible.
You have to sort of let the car waft along at its own pace, easing off the gas as much as possible without actually slowing. Any sense of "press-on" driving make a big impact on the MPG.
It's a biggish engine so it'll take a long time to warm up thoroughly - literally 20 miles on a cold day. Short runs will be bad for MPG.
R0G said:
Be surprised how many auto drivers only use D when other available options are there
Indeed. Well, I have to confess I'd never really noticed anything other than drive, park, reverse and possibly a sport mode on autos before. It throws things into relief when you you're paying for the fuel.Doing my best attempt at hypermiling on Friday night I managed ... wait for it ... 30.3 mpg. Admittedly, that's a short trip with plenty of traffic and hills on a relatively cold day, but it's still not really what I bought a diesel for.
A full service, PCV filter change and EGR clean is indeed on the cards. Apparently they're very much prone to thermostat failure too, which leaves the engine running cold. Also told you don't tend to get any warning on the CDTs if the MAF sensor fails (it doesn't flag an error or anything) so that's worth checking.
Chris71 said:
Indeed. Well, I have to confess I'd never really noticed anything other than drive, park, reverse and possibly a sport mode on autos before. It throws things into relief when you you're paying for the fuel.
Sports mode has been used on many for bends or 30 limits as it can give better controlChris71 said:
Doing my best attempt at hypermiling on Friday night I managed ... wait for it ... 30.3 mpg. Admittedly, that's a short trip with plenty of traffic and hills on a relatively cold day, but it's still not really what I bought a diesel for.
What, the 30MPG or the short trip with plenty of traffic and hills on a relatively cold day? The MPG figure is in the right ball-park for the use you described.Get in on a motorway at a steady 70ish for 100 miles and it should easily do mid-50's.
Are these the BMW engine?
Deva Link said:
Are these the BMW engine?
Same as Freelander1 TD4 I think.stevemiller said:
Over on the 75/ZT forum there is a lad Big Russ who will load a 160 bhp map for little money that will see the car go better with no change in mpg
Also, the Synergy 2 remap device claims to improve both performance and economy on these. £200 though...Re. "accelerate quickly/accelerate slowly for best economy":
I've seen arguments for both among the eco-drivers, and I think the apparent lack of consensus suggests that it doesn't matter. Assuming you're not labouring the engine below the power band or revving it beyond the useful range*, accelerating up to speed X is going to require energy Y, whether you do it briskly for a short period or gently over a longer period. In other words, acceleration is expensive however you do it. What really counts is maintaining the momentum you've paid for - and not buying more than you need.
Some good auto-box info here, particularly on acceleration sense and avoiding unnecessary braking:
http://www.ridedrive.co.uk/driving-tips-06c.htm
* (should be roughly 2000-3500rpm for a stock M47R)
Deva Link said:
Chris71 said:
Doing my best attempt at hypermiling on Friday night I managed ... wait for it ... 30.3 mpg. Admittedly, that's a short trip with plenty of traffic and hills on a relatively cold day, but it's still not really what I bought a diesel for.
What, the 30MPG or the short trip with plenty of traffic and hills on a relatively cold day? The MPG figure is in the right ball-park for the use you described.Get in on a motorway at a steady 70ish for 100 miles and it should easily do mid-50's.
Are these the BMW engine?
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