Car Darts

Instead of saying 'Awesome' from now on, i'm just gonna say 'Carerra GT'

I was bloody impressed with the diesel A8. Or should I say the V8 Twin-turbo TDI A8.

I'd quite like to see that on the track, just for a laugh.

Or more seriously, I'd quite like to get to drive one.

Peter

AstraVanMan raved thus:

:: I was bloody impressed with the diesel A8. Or should I say the V8 :: Twin-turbo TDI A8.

Clarkson was a nob driving it, though; I could have done that journey with fuel to spare.

He should have drafted trucks all the way to Edinburgh and back. Would have saved loads of fuel like that...

The really sad bit was when he started to pass on all the things he had learned - never brake, don't coast in neutral etc. - I was one step ahead. I drive the passat like that all the time :-(

The locost however ................. it get's it's first track outing this week...

If I drove the Audi like that all the time I'd save a lot of fuel on longer runs. It should easily manage 45-48mpg on a long run doing no more than

80mph, but it's tempting to plant it wherever acceleration is possible, do a bit /cough/ faster than 80, and generally use the performance of it, and as a result I only get around 40-ish. I did once get it showing an average of 62.5mpg on the trip computer, but that was filling up on the edge of Milton Keynes (A421), heading out to the M1 doing a constant 50-60ish, then sticking to 65 or just below on the M1, and driving gently all the way into Luton town centre.

Peter

Why does never braking help so much?

It's not so much the braking, it's the accellerating afterwards that does the damage.

Surely then i'd have to drive slowly everywhere :) ?

Because the engine has to work more to get you back up to speed. Whereas you may have been able to have the same effect by simply pottering along at a slower speed and possibly using no fuel at all. Although never braking maybe taking it slightly too far!

Drive everywhere at a constant speed - The old farts round here do all the time, I thought it was because they were blind and crap, but now I realise they're too skint to buy more petrol!

I remember when I had my TDI Fiesta van I was on my way into work (about 13 miles) and was getting a bit worried about how much was left. The fuel light had already been on about 20 miles, and the absolute most I'd let it go was nearly 30 before filling up. I was about 5 miles away from civilisation at about 6am, and had done just over 30 miles since the fuel light had come on. Made it, driving extremely gently and filled up with 10 litres, then picked up the package, and went from Slough to Crawley around the M25, carrying on the driving gently thing, to see how many mpg I could get (roughly calculating it by the miles covered from the fuel light first coming on to when it came on again, and that's 10 litres worth). Did a constant 60-65 around the M25, took it nice and easy into Crawley, same coming back, and when I came back into Slough the fuel light still hadn't come on, and I figured out that if it was just about to come on I would have done around 62.5mpg between fuel lights. So it was probably slightly more than that.

Mind you, if I did a long-ish journey at 95mph economy would drop to just below 40mpg :-(

Still, at least it could reasonably happily maintain 95mph, unlike the lethargic piece of crap M reg Fiesta I've recently got rid of, which would struggle up hills at 60, and flat out at whatever speed it could manage (90 on some downhill stretches) it would still only be doing 38mpg. Still, managed 48-50mpg around town, so it's not all that bad.

Peter

In article , snipped-for-privacy@italiancar.co.uk spouted forth into uk.rec.cars.modifications...

And the Saab convertable went much further than the rest.

high performance or what :)

If you can negotiate a bend or junction without braking, you probably lifted off earlier to allow that to happen - that saves fuel. Also, braking turns kinetic energy into mostly heat which is then dissipated into the air and is lost to you forever. If you don't have to brake, you keep the energy in liquid / potential form in your fuel tank. I can make a 25% difference by observing these rules and short shifting on a light throttle as well.

It's really really boring though.

It's fairly easy to drive so as not to hardly ever need to brake, on longish trips.

Braking is throwing away energy, while the engine is used to input energy that costs you fuel. Drive so that you spend fuel / energy to keep the speed up and plan ahead so where you would spend fuel you can instead let the speed drop naturally and avoid braking later on will save you fuel.

You'll always need to brake at the end of the journey, obviously. And in emergencies and stuff, but less so when you plan ahead.

Cruise control makes a noticeable difference in my road car, too, because it keeps the throttle even handed and makes variations smooth. Manually I tend to speed up and slow down using various throttle positions. Course, you have to allow for faster / slower cars so you often can't cruise on our roads.

I don't give a toss about all that anymore. If I drive like a nun I get

40-45ish mpg, if I 'press on' I get 35mpg. But I enjoy 35mpg, so will continue driving like that.

The day I feel I need to drive for economy is the day I sell the cars / bikes.

I'm amazed at the amount if people I know who make little or virtually no use of 5th gear, personally I'm up into 5th at every reasonable opportunity.

I was gonna say :) Surely i wouldn't be going as fast as possible if i was doing that :D

I wasn't convinced about the argument of not coasting due to the fuel cutoff when on the over-run. I'd have thought the friction of the engine (causing the car to slow down) would have used more energy than fuel to keep it idling while coasting.

Not entirely scientific, but on a long downhill stretch of motorway, if I lift completely off the throttle and read the instantaneous fuel consumption it will go off the scale. i.e. >200mpg - the mythical "using no fuel" because the management systen has recognised it doesn't need any. If I do the same thing but knock the transmission into neutral, the instant readout will be around 60-70 mpg. Because the engine is usng a drop of fuel to tickover. If the hill is just right I will usually maintain the same speed because there is little or no engine braking at motorway speeds in 'my' car. (It's not my car - I'm a "user chooser" ). I have to say that I didn't really have to drive like a vicar on an economy drive to discover these things. I just chose to have the computer on the average mpg setting - it's right in front of you and it has to be set to 'something' - you can't turn it off. Coasting down a long motorway hill off the throttle is quite useful though - if you're getting wound up and need an instant release valve this works a treat and rewards you with an extra 0.5 mpg ;-)

Disclaimer : - This is all based on the findings of my VW trip computer. How true it all is will be entirely open to question.