Real world mpg

(03-01-2012 12:07am)Dave_T Wrote:  Sorry, I was just editing that

I'm still not convinced though. I'll find out the relative weights for you

I think you have Way Too Much time on your hands

I am sure that the MPG will improve an for me if it can average 33-35 mpg I will be fairly happy, I do think that it will be north of 35 given time

Anyway, enjoy the bloody car

(03-01-2012 12:07am)Dave_T Wrote:  Sorry, I was just editing that

I'm still not convinced though. I'll find out the relative weights for you

Hmmm.. Not much information available on the Scorpion Verde, other than they are crap off road (even Pirelli rank them 0/6 )

@Dave_T Very funny. I got your cryptic opinionated reference! Made me chuckle...

Science considered, I'm not seeing the basic Pure crew boasting about 40 mpg advantages. I drive this car much more sparingly than I did my old Beemer and that hit a closer note to the proclaimed mpg....

maybe we could be really unlucky in that LR have developed wheels designs that resulted in a relatively heavy 18 and a super light (for the size) 20 ! , don't get me wrong, i am not disputing the figures you guys on 18's are seeing, but i would have expected to see a bigger difference between 18 and 20 in terms of mpg..., the mystery of poor mpg is odd and disapointing for sure !.

(02-01-2012 07:57pm)Pedalpower Wrote:  no you have missed the point, of course the rolling diameter is the same !, the aspect ratio of the tire makes up the difference, it is the centrifugal mass which is massively different (alloy is heavier than rubber/Air!), the weight of a 20inch rim is much more than a 18, and the hence power required to make it spin is much more than a 18. Rotating mass can be multiplied by 2 or 3 to crudely get a idea of added weight to the car, hence and extra 4 lb on a wheel is like carrying 8 or 12 or so in the car, multiple that for 4 wheels and you are looking at a big gain. Drag is a factor, but nothing like rotating mass. Having big wheels will have a much much bigger affect than the tail gate or roof, every time you accelerate you are having to spin up the extra mass. I have seen it first hand, why do you think the pure can be purchased on 18inch wheels ?, its not for looks thats for sure . Take a look at VW bluemothin cars, i think the golf comes with something crazy like 15inch wheels !. If you have 20inch wheels expect to have compromised mpg.

Could be something in this: taking my 20" wheels off and puting on my 17" winter wheels/tyres I seem to have gained an extra 4-5 mpg but then again it could just be due to the car getting "Run in"

plus winter tyres most likely have a higher rolling resistance, so I think 17's with summer tyres would be a winner in the mpg stakes just not in the looks department

(03-01-2012 10:22am)woodhouse Wrote:  Could be something in this: taking my 20" wheels off and puting on my 17" winter wheels/tyres I seem to have gained an extra 4-5 mpg but then again it could just be due to the car getting "Run in"

It will make a difference, no doubt about that, in terms of how much difference will depend on how the wheel has been designed, i.e. where the weight is, and the size jump, more weight towards the rim the more force needed to make a change in rotational speed and hence more power required. Also i am not sure if the 20inch wheels are wider (in terms of tire) than the 19 or 18, wider tire also adds weight the rim (although this is marginal). As i said, take a look at the Golf Blue motion compared to the GTI, Blue motion has 15inch wheels the GTI 19.

Despite someone saying its 'Tosh' !, its simple physics, in bike racing the first place to improve a bike is the wheels, light wheels are worth 4x the saving of anything else, this can be felt in the legs instantly when climbing or accelerating etc etc.

In terms of saving on a car, once you are up to speed, say on the motorway, the wheel size is largely irrelevant as you already have momentum in the wheel, at this point its more about tire drag, however, every time you change speed, i.e. accelerate at all, you are having to use more energy, Hence, you will see more improvement in your mpg in your urban type driving, (than just sitting at 60mph all day). That being said, you still need to accelerate up to 60mph. there is no downside to a smaller wheel at a constant speed, just the benefits are not as great as when you invoke changes in speed.

I'll throw in my two-penneth

The tests are carried out in a controlled environment on a dynamometer at a nice summer temperature of 20 degrees c and up

The first part consists of 2.5 miles of accelerating, slowing down and idling in the lower three gears (unless it’s an automatic), after a cold start, at an ambient temperature that we expect to experience on a English summer day. The maximum speed is 30mph and the average 12mph.

Following on immediately from this, the second figure is derived over a further 4.3 miles driving in all gears, accelerating very gently up to a maximum of 75mph, and averaging 39mph. The total fuel consumed in both tests, divided into the total 6.8 miles, gives the combined result.

The US use a different method of calculation and a quick check on the petrol auto figures for the US (converetd to UK gallons) show extra urban of 33.6 v the EU 40.9 and a combined of 27.6 v the EU 32.5

Bear in mind that the tests are done in a Lab and not on the open road therefore -
No Wind resistance
Nice summer temperature etc.

I know from my own experience in my old 320d that in summer I could achieve 63mpg on the motorway but in winter that would drop to 53mpg, probably as a result of air density, temperature, wind resistance and load on the engine from electrics.

Apparently the EU are looking to change how the figures are calculated from 2013. In the meantime just accept that the quoted figures are complete b***ocks and enjoy driving your evoque!

(03-01-2012 01:54pm)mywillia Wrote:  Apparently the EU are looking to change how the figures are calculated from 2013. In the meantime just accept that the quoted figures are complete b***ocks and enjoy driving your evoque!

Here Here!!! Couldn't have put it better myself!! If it bothers you guy's that much SELL IT!!!!!

(02-01-2012 10:57pm)The Valeter Wrote:  However if enough & I mean enough people complained at the same time & we can show proof then I guess they may listen.

They may, as they would not want the adverse publicity?