4 x 4 Mpg ?

[Rob The Dog]

Having looked at the Yeti with great interest over the past month or so, on this forum and in the flesh at a dealers, I wondered what makes one sort of vehicle more or less economical than another ? my own car, an Audi A4 Avant 2.0 TDI 140 6 speed manual (B7) 6yrs old, 78,000 miles, well looked after, returns between 40 - 53 MPG (checked full at the filler kneck) depending how its driven, and I am sure if just confined to motorway and speeds of no more than 60 MPH on a long run would do even better. I had thought the difference in MPG between A4 and the Yeti 20. 140 TDI's must be: 1. the distribution of power to all four wheels , 2. aerodynamics (shape of the Yeti and the fact its high offf the ground) 3. Weight ( assuming the Yeti to be more robust and more complex ie the drive train etc etc ).........................................But NO , the Audi A4 Avant 2.0 TDI 140 manual is 110KG's heavier ! thats 242lbs or 17 1/4 stone, that in my book is a big person ! mmmmm ? kind of gets you wondering , there must be more to it, What about RPM in top gear the A4 in 6th does: 50MPH @ 1500RPM, 60MPH @ 1800 RPM, and 65MPH @ 2000RPM

What do you Yeti owners do in terms of RPM at given speeds ?

Edited 6 February, 2011 by Rob The Dog

[Llanigraham]

I'm confused.

Thread title is about MPG, but now you are asking about RPM in certain gears.

All I know is that on my 48 mile, 1 hour trip to work, using mostly cross country A class roads I get an average of around 49 mpg. When it was very cold it went down to around 45, but for the last 2 days it has been just over 50 mpg.

[Rob The Dog]

I'm confused.

Thread title is about MPG, but now you are asking about RPM in certain gears.

All I know is that on my 48 mile, 1 hour trip to work, using mostly cross country A class roads I get an average of around 49 mpg. When it was very cold it went down to around 45, but for the last 2 days it has been just over 50 mpg.

[Rob The Dog]

Yeh, with a view hopefully to understanding what it is that makes a lighter yeti less economical than a heavyer estate car both of witch have the same engine

[Llanigraham]

Yeh, with a view hopefully to understanding what it is that makes a lighter yeti less economical than a heavyer estate car both of witch have the same engine

So really the RPM at a given speed actually doesn't matter, since that is continually changing over a comparable journey, plus is also affected by driver method and terrain. Really what you need is an overall average consumption over comparable journeys.

Therefore see my figures above, and find someone with the different car who does a comparable journey.

[Rob The Dog]

So really the RPM at a given speed actually doesn't matter, since that is continually changing over a comparable journey, plus is also affected by driver method and terrain. Really what you need is an overall average consumption over comparable journeys.

Therefore see my figures above, and find someone with the different car who does a comparable journey.

I was trying to get a sense, of weather the Yeti or 4 x 4's in general rev slightly higher or the same at any given speed compared to ordinary cars, for example two cars driving at say 65 MPH in top gear with the same engine, but different gear ratios would return different MPG figures over the same distance

[bahnstormer vrs]

Yeh, with a view hopefully to understanding what it is that makes a lighter yeti less economical than a heavyer estate car both of witch have the same engine

I'd suggest primary factor is that Yeti has a larger 'frontal area' i.e. shaped like a brick!

As to mpg I've just completed my first 1,000 miles/running in and seem to be getting 38mpg on my typical weekly commute into N London.

By comparison my Octavia vRS TDI would return 40-42mpg and an Audi A5 2.0L TDI Quattro driven recently for a few months gave 37-38mpg.

I'm not sure about gearing in too much details except that at any given speed in top gear my Yeti seems to run 250rpm slower than my Octavia vRS TDI i.e Yeti is longer geared.

[fuzzybunny]

I'd suggest primary factor is that Yeti has a larger 'frontal area' i.e. shaped like a brick!

The yeti certainly has poor aerodynamics so my mpg over 70 mph drops off to around 40mpg

Keep it to around 60 mph and you will get high 40s or more.

I understand its mostly front wheel drive with 90% drive to the front.

Surely the A4 in question use the older PD engine which in my opinion seemed to give slightly better mpg than the CR. On the plus side the CR is much quieter and behaves more like a petrol unit. it even has an exhaust note more like a petrol engine. The PD engine always sounded like a lorry when pressed hard. I'm sure lots of people will disagree with that though

[rockhopper]

Yes I agree, 70-75mph will give around 42mpg in Elsie.

Today I had to drive into Central London into the congestion charging zone and Elsie averaged over 45mpg, which included some brisk acceleration up to the speed limit - all 30mph. (I did leave home at 7.30am!) This seems to be more than before the remap, which would have been in the late 30's.

Mike

[Llanigraham]

I understand its mostly front wheel drive with 90% drive to the front.

I am perplexed as to where this idea is coming from. My understanding is that with Haldex 4 the vehicle is front wheel drive until slippage is sensed then drive to the rear is increased.

Back to the OP.

From this mornings journey:

In 6th gear.

40mph = 1100 rpm

55mph = 1500+ rpm

MPG Av = 54.

That certainly proves that air temp improves consumption. AV temp was around 10*

[bahnstormer vrs]

I am perplexed as to where this idea is coming from. My understanding is that with Haldex 4 the vehicle is front wheel drive until slippage is sensed then drive to the rear is increased.

There is a link in another thread somewhere to the Haldex website, which shows that any wheel always has a minimum of 5% tractive force to it. Therefore in 'normal' driving you will have 2 x 5% going to the rear and thus 90% to the front.

This can then be variably split as required even to the point of, if you have three wheels on ice and one on tarmac, the tarmac wheel that has the grip will take 85% of the tractive effort with 5% to each of the other three wheels.

[Frank Bullitt]

Gearing needs to be judged across a number of factors; drag, weight and, of course, engine characteristics. I would imagine a Yeti turns over at slightly higher revs than an A4 with the new CR engine but if it had longer gearing would end-up labouring lots more thus using fuel and not doing the engine much good.

I suspect in similar driving a Yeti would use a little more fuel than a saloon car, even if the latter is heavier, because of drag; it's the same reason a CR170 A4 will do almost 140mph but a Yeti...won't!

I've driven afew B8 A4's (2.0TDI S-Line Multitronic Avant, 3.0TDI SE Quattro Saloon) and they are horrible things - make mine the Yeti, ta.

[900000]

I'd suggest primary factor is that Yeti has a larger 'frontal area' i.e. shaped like a brick!

Oh yes. THIS is the culprit without a doubt. Coming from the perfect aerodynamic shape of a Kamm-back 0.27 Cd Audi A2 to this brick 0.37 I can see the difference clearly in my pocket come fill up time! But my right foot also to blame. Saturday I put my foot down to join the A2 at Greenwich to see of a pesky Merc E-class minicab. I glanced at my instant consumption when I hit about 50mph: it read 6mpg!!!!!!!!!!!!!!!!!!!!!! Eeck!