+ and - of automatic gearbox - is manual better?

Right - so your simplistic definition of 'energy out/energy in' isn't enough here - you do need to consider the other factors.

Is 'get to your cruising speed using the least amount of fuel' all you want? Does it matter that you may spend a bit more time and hence fuel at the cruising speed? Or are you after the most efficient way to travel a given distance, assuming accelerating at some rate (this rate to be determined) to a given speed then cruising?

cheers, clive

My Mum has one and great fun it is too. :)

Give the throttle a firm poke to engage drive and back off if necessary...

A CVT Micra thrives on full throttle.

That will depend on each and every occasion.

Full throttle is very rarely more fuel efficient than part throttle, whatever the engine speed. Our ECU, as with a great many modern cars, does all sorts of clever things at part throttle conditions. At full throttle it aims to produce the most power, but producing the most power possible is not always as efficient as using lower engine speeds.

I see the point you're getting at, but unless you can compare fuel used over a number of given acceleration profiles, it's a bit academic really. You believe that it's more efficient to accelerate briskly massaging the engine speed between three and four thousand. It may be with your engine and transmission, but it requires effort and adopting less throttle will almost certainly result in fuel saved but a longer time. The question is this: if it takes twenty seconds using the full throttle technique, and forty seconds using half throttle, do we save sufficient fuel during the twenty seconds of cruise?

My data is inconclusive.

Nope. In some respects it's the opposite. Getting used to how a car drives is a normal part of motoring. There's no difference.

It's easier. Less to do.

Hmmmm. Sounds knackered, unless you were trying to drive along at 30 in first?

Astravanman is right. Efficiency isn't the same as economy. An engine may be nicely efficient at full throttle, 3,500 rpm, but it will be using less fuel at seventy percent throttle, 2,500 rpm...

As others have said, automatics are easier. But a poor quality automatic will cost lots to fix...

An auto in economy mode will always change up as early as possible maintaining max efficiency for the engine load. An auto in sports mode will go for max power.

I can pull into a gap in my 90 bhp A class that my 215bhp Manual Volvo could. Makes little difference - in fact it's easier, just mash the GO pedal.

Tiptronic / Sequential selection sorts this. And you rarely use it.

Use cruise control. Modern boxes don't hunt, and it's only telling you that changing down is more efficient.

Ahhh it's a yankeee slushbox. No wonder.

It's an american car. It'll be crap.

Indeed.

You really haven't got a clue have you? The kickdown on a modern auto is almost instant, and you can preselect if you must. I overtake as much in my

Sequential selection - move lever left and right for down and up. Mine is a

I've read a few other posts. The quality of the automatic transmission makes a material difference to how it works. Good ones, even simple good ones, are great. Bad ones that faff up and down the ratios are not so good.

And a very extreme case unless you have a habit of cornering on the limit of adhesion at full throttle. Many modern transmissions don't change ratio when cornering at a certain acceleration unless you're at the redline. In this respect they're little different to a manual; the difference being the few hundred rpm between redline and limiter. I put it to you that an engine reaching a hard limiter is rather more dramatic than a transmission shunting up a ratio *cough cough*.

I've responded elsewhere with this, but manufacturers set it up to be like this... for good reasons. Full throttle is for full acceleration and not for maximum efficiency. :)

You can do this but you will damage the clutch by overheating it. It's not good news.

You can get a similar effect with an automatic by holding it on the footbrake and giving it some throttle. When you release the footbrake it takes off.

Hmm. I've found the opposite. They do require some getting used to but are not materially slower off the line compared to manual.

I think we've covered this elsewhere, but most have easily identifable notches. Kinda like a manual gearbox has easily identifable places for the stick to be.

That sounds like a knackered 'box. Some cars will do this at certain speeds (30 as an example, where they'll shift between 2 and 3 or maybe 3 and 4).

Seems a bit of an irrelevance I'm afraid.

Automatics tend to be easier to drive in the snow because if you're gentle with the accelerator, they're gentle in applying the power.

A poor, jerky automatic is appalling. A smooth one is great. I can change gear as well as an automatic once I'm used to the car. I like them, I'd have one, I kid myself that I prefer an automatic - but a good quality automatic works just as well as a manual.

But I have a real dislike for most flappy paddle changes... :-/

You hit it. That's why you make sure that your car with autobox has at least six airbags.

Mine monitors cornering too and doesn't change mid bend.

Any mercedes, most BMWs and Volvos. All better (and easier to resell) with Autos.

As much? More, surely...

ie at max torque - hence why turbo+auto works so well.

The best way to brake generally in snow is as early as possible, if not earlier. Emergency stops with ABS are simple. Mash pedal.

I don't think the car makes much difference. 4 wheel braking is always going to be better than 2 wheel braking. Regardless of whether the car is FWD or RWD. When the road is so slippery, that taking your foot off the accelerator immediately slows the driving wheels to tickover speed, and they start sliding down the camber. 4 wheel braking is the most effective way to slow down. Mike.

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Then you must be a more enthusiastic driver than me. My Audi just gets on with it all seamlessly - and the way I drive a gear-change in the middle of something else just isn't important.

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I used to have learners who had that trouble in manuals. However - they soon learned.

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Or considerably longer if it's a Renualt!

Hooray!

Hey dude, how else did we win our class at the Pothunter Rally?