driving style questions

[no2lurch]

i been thinking...

lately i have been driving my 2.2 sri estate in the most frugal manner i can. i know the car puts out 160bhp at 5900rpm roughly and 160lbft torque at 3900rpm, so if i am being frugal while still getting the most out of my car, am i right in thinking i shouldnt rev my car over 4000rpm?

also, if i want a high mpg as possible, should i drive in a manner of using gears at high revs to accelerate, or low revs. i mean at say 30mph, should i drop it into 3rd to accelerate or get it into 5th to pull it?

[steve_earwig]

Don't you have one of them instantaneous consumption things? Or, if you're feeling wasteful, you could do a short journey, say 5 miles, with as much hills and stuff as possible. Start off by resetting your consumption meter thingy and do it in as many driving styles you think you can afford, then see which one produces the best number.

[Gary406]

on my 2.0 16v petrol vectra 3 years ago i found keeping it under 3k revs got better mpg
also dont let the engine struggle in high gear at low speeds ...

even on my 1.9 i keep it under 3k revs. i drive like a sissy.
from past experience driving cars hard only causes problems at sum point

[Welly]

You should drive with 'favourable' revs i.e. not too little and not too many for best economy, keeping below 3000 rpm is good practice but also make sure the engine gets to stretch its legs every so often. Each gear selection should match a reasonable rpm so trying to haul the car from 30mph in 5th is going to use more fuel that using 3rd, 4th then 5th at reasonable revs.

The biggest factor in best economy is reading the road ahead, don't touch the brakes if you can avoid doing so and don't accelerate hard between traffic lights - all that kinda thing.

One thing some people forget, when labouring an engine, is that the oil pressure is very low and the big end bearings don't like it

[FarmerPug]

In a hdi there isnt much need to go above 2k revs if your driving sensibly. But i find eco driving unbeliveably difficult, i even drove last night with jazz on, was nice and relaxed but them some arsehole tailgates you and wont overtake.
As for braking dont do it, unless a pram rolls out on the road, an animal is on the road, or someone is using them traffic lights with the button in which case send them an invoice for the lost fuel. More relaistically on the motorway try not to get yourself trapped behind a lorry which would mean having to brake, unless you want to do 56mph, and im quite sure behind a lorry arerodynamically speaking your car will experience less drag as the lorry has cut through the air for you.

[no2lurch]

In a hdi there isnt much need to go above 2k revs if your driving sensibly.

i drive a petrol.

[FarmerPug]

wow i always thought the 2.2 was the hdi.
But with a petrol, get an lpg conversion, and most of the driving style tips still do apply, execpt with the torque coming later in the rev band its best not to exceed the point where maximum torque is developed. And dont push the accelerator in fully when driving.
All tips i know of but dont use.

[highlander]

LPG conversion kits cost big money. And you need to tell your insurance company you've had it done (actually, before you do it), and they'll then happily increase your premiums.

As for the 2.2 - the EW12 J4 engine is the rarest 406 engine (except possibly the elusive continent-only 1.6), and is petrol driven. There is also the 2.2 HDi (DW12 TED4), which comes with the much-revered FAP.

[Doggy]

There is also the 2.2 HDi (DW12 TED4), which comes with the much-revered FAP.

or not in some cases, but then you'd have to make do with 178 bhp / 295 lbft / 40+ mpg / £180 road tax.

[mjb]

I've always found driving as close to idle as possible is best when not accelerating. Accelerate slowly and at moderately low revs (under 2000rpm) for best economy - if you try it at too low revs you'll end up with your foot on the floor pumping in excessive petrol...

[kevtherev]

as mentioned above really , hardly use the brakes,i decellerate up to islands/junctions keeping itr in 5th as long as possible.certain stretches on my commute i can cover over half a mile decellerating when sat in stop start traffic let the car in front pull away a decent distance (my mrs hates me doin that)then i just put it in 1st/2nd and let the gas pedal out and it pulls itself along, also i skip gears i jknow mine will pull comfartble in 4th at 30 so i go 2nd to 4th or 3rd to 5th depending on speed limits
is it correct what clarkson said on a top gear that when decellerating you use no fuel ?? i base my driving style on this one piece of information lol

[mjb]

is it correct what clarkson said on a top gear that when decellerating you use no fuel ?? i base my driving style on this one piece of information lol

For once, yes he was being informative.

When the engine's at operating temperature, the car is moving, the revs are above about 1200rpm and the accelerator is not pressed, then the ECU won't fire the injectors.

[Welly]

is it correct what clarkson said on a top gear that when decellerating you use no fuel ?? i base my driving style on this one piece of information lol

For once, yes he was being informative.

When the engine's at operating temperature, the car is moving, the revs are above about 1200rpm and the accelerator is not pressed, then the ECU won't fire the injectors.

The correct term used is 'Deceleration Enleanment'

I thank yaw.

Actually, it is desirable with race engines to 'dump' fuel on the overrun for in-cylinder cooling (hence the flames out the back) dumping fuel like this cools the piston tops and exhaust valves. I don't think it's something we need to worry about though when exiting a slip road off the M11

[steve_earwig]

I thought it was over-run cut off On my first bx 16valve I had the throttle switch to bits, inside were one pair of contacts for idle and one for full powah. The bx cut the fuel off over 1500rpm (I think it was) with the idle contacts closed, so revving it with the switch removed & set to zero the revs bounced up & down under 1500 - bah..bah..bah..bah..bah..bah.. I guess things have moved on a bit since motronic MP1.3 tho.

[FarmerPug]

LPG conversion kits cost big money. And you need to tell your insurance company you've had it done (actually, before you do it), and they'll then happily increase your premiums.

My dad got it done, it cost £1500 that includes everything, the insurance stayed the same, nissan still honoured the warranty, the lpg company offered a 3 year warranty on the kit. And at the end the lpg kit can be removed from your car, and the installer only charges £500 to put it onto another car. V6s cost a bit more to install, thats the price for a 4cyl instalation.