Be Excellent To Each Other

S'alright, I haven't got any dogs.

O, RLY.

If it's 2900RPM at 70, it's 2485 at 60 or 3314 at 80. That's 415 RPM difference, not 100.

And if the Golf was doing 1900 at 70, it's 1628 at 60 and 2171 at 80, 271 difference, not 1000.

Also

##


Re Golf, it's what I recall from having driven it and what the dials told me.

Re 306, I was a bit out, it's 2,200 @ 60; 2,750 @ 70 and 3,000 @ 80mph according to the dials.

mpg figures came from the computerator in the car. I'm not sure what your point is here, though.

It doesn't have a fancy-arsed screen with live MPG reporting either.

Well, just that all your facts were wrong, even if they were correct they don't support what you were saying, and what you were claiming was wrong anyway.

though.

We might have got our wires crossed somewhere down the line:

Golf: 70mph was 1,900 rpm, 80 was 2,900rpm. In car Computerator said 10mpg difference between these two speeds.

306: 2,200rpm @ 60mph; 2,750rpm @ 70mph and 3,000 @ 80mph as seen today.

When travelling at 70 mph, the 306 returns less mpg than the Golf.

We agree on these?

I'm not sure where I'm "wrong" unless my memory is fucked, or my eyes have problems seeing things. Alternately, the dials are fucked on both cars.

No, it definitely wasn't!
I posted above what it would be if the first figure was accurate - it's a simple ratio to work it out.


Quite likely, but this is very little to do with any difference in gearing between the two cars. Especially as they won't actually be much different.



D) all of the above?

Having driven the car, quite a lot, and noted that the difference between 70mph and 80 mph was 1000rpm, the either I'm lying or the rpm counter thing was. And I'm fairly sure it isn't me. honestly, the car did have fairly high gearing, and a brief google does back this up.



Autocar




I was merely noting the difference between how much work the engine was doing at 70mph in both cars, there's a difference which works out nciely when compared with average mpg.



Not currently possessing a Golf, I can't really take a photo of the rpm and stuffs.

Again: If the golf goes 70MPH at 1900 RPM, as the magazine agrees, then at 80, it is 2171 RPM. Not what you said.

This is a smaller difference than on the 306, but you seemed to be claiming that the Golf got better MPG because it had a bigger difference between those two speeds.

I'm not trying to be a dick here but it's something I know about and you are spreading all sorts of confusion

It's worth noting that lower revs don't automatically equal better consumption.

Yeah surely the relationship between rpm at the engine and rpm at the wheels is linear and predictable, unless your clutch is slipping.

It is until you don't change gear

Correct - however the one thing I'm sure about what MaliA is saying is that this was all in top gear.

Oh.. maybe he meant the TV program, in which case that would explain the wrongitude

No, really, I saw it with my own eyes. Every time I drove the car in 5th gear, the difference between 70mph and 80mph was 1000rpm.

The only way to prove this is to get a Bluemotion Golf and drive it at 70mph and take a photo of the dashboard, then do the same at 80 mph. And I don't currently have access to one. You've got to trust me on this.

Well no, because simple arithmetic demonstrates that either your memory or the car's RPM gauge was completely wrong. You need to trust me on this, seriously

Wait, the Bluemotion isn't an automatic or CVT or something is it?

Assuming the Golf was completely standard, of course.

Standard Golf Bluemotion 1.9 Turbo Diesel.

What simple maths?

That appears to be a standard manual 5 speed.

So, indeed, what you are saying doesn't add up. The rev-counter must have been wrong.

Cross multiply 70/80 and 1900/x to get x.

What Kalmar is getting at is that if you simplify it right down and imagine a pair of cogs, one being your engine the other your wheels then you know that any % change in the speed of one cog will result in an identical % change in the speed of the other. Despite the complexities in between this still holds true for most cars sat in a particular gear.

But that does not at all tally with my experience. On the Vmax test I did in it, redline in top gear was about what they said the top speed of it was.

So, either:

I'm wrong
Speedo and rpm meter were wrong
kalmar is wrong

As I've no speeding tickets from it, and the 70mph rpm checks out, we can discount the middle option, and my experience of driving it on a fairly regular we can discount the first option....

Well, now you're just being obstinately wrong in the face of Science, and as such are fair game for ridicule

The other option is that the clutch was slipping but if that were the case then it surely would have got worse over time.

Not really, as, by your calculations, in top

70/100= .6363636

Then 1900/.636363 is 2,700rpm

Which it wasn't.

I'll get MrsA to email her old colleague who has one as well and ask her, if you want.

The simple answer to this is magic.

I've gotta side with the science on this one, Mali.
If the car was doing 70mph@1,900rpm then the car is doing 1mph at 27.142rpm in that gear. That's a fixed amount in a manual, and can't be changed.
For the car to do 80mph@2,900rpm that number would change to 36.25rpm per 1mph, which isn't possible.

Unless it has a torque converter, or something odd. I know little about Bluemotion cars, but I assumed they were just little engines with big turbochargers.

Magic.

It was, if you were still in top gear.
But we've already established that either you or the rev-counter is wrong, so giving another example of this doesn't really help you.



I'm in no doubt here, but please go ahead!

Would it be more fuel economical to fill your car to 1/4 full rather than completely full so you're lighter?

Yes. It'll go faster, too.

Depends how far out of your way you have to go because you're filling up four times as often though.

Granted. The improvements will be very small. I'd go as far as to say that stopping at the petrol station four times as much would put a big dent into your economy at that scale, too - especially if it were on a motorway or something.

I expected more science from you.

Also, for completion, this sounds wrong. That review you linked states the top speed as 118MPH, not 100 as you say later.

And in 5th, you'd be nowhere near the red line at that speed, the top speed would be obtained in 4th in this car.


I think in fact this is all based on you remembering doing 80 in 4th versus 70 in 5th, or something like that.

This was my thinking too. Consider that a full tank of petrol weighs about as much as an extra passenger, which isn't that much as a proportion of the mass of the car.

I'm not your science whore. I don't do science whenever you demand it. WE USED TO TALK. YOU NEVER HOLD ME ANY MORE.

OK, cool, yo.

Either my memory is wrong, or the rev counter is wrong, or the car had super sekrit stuffs.

Can you tell MaliA he's wrong doc? He's not listening to any of us. *throws in towel*

It's even worse economy if you buy mars bars and stuff every time you stop.

Hmm, not sure that's necessarily true; plenty of sporty cars are geared to redline in fifth/top I thought, especially older stuff?
Mali's car was a 205 GTI wasn't it? I'd be surpised if this didn't redline in top gear.

Surely he'd go to grab you and his arms would meet air a couple of feet over your head?

It's not a sporty car, it's a specifically-built-for-fuel-economy compact diesel car.



Please read the discussion!

You left me cold and crying in a RE5 lobby...

Zardoz and Richard Gaywood, yesterday.

Ah soz, didn't bother to read everything, that last post caught my eye. Not like me to be half-arsed eh... oops.

(Gah, that's twice now in the same day, in the same thread. Note to self: and the moral of the story is... )

Edit: I thought the 'please read back' first incarnation was better.

(Thought it was a bit blunt)

Also bear in mind that speedos are lying bastards (assuming that my GPS is as accurate at calculating speed as it is at finding my pots) when I'm doing 80 on the clock I'm actually doing 73 or something. IIRC it starts lying between 40 & 50.

Yes, they deliberately over-read by anything up to 10%. It's obviously a lot more noticeable at higher speeds though.

It should be fairly consistent though, unless yours in particular is faulty.

Hey, maybe that's what's wrong with my car and the clutch is fine!