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+--- Thread: Drag coefficient (/Thread-Drag-coefficient)
Pages: 1 2
Drag coefficient - Donny Dog - 09-05-2012 01:47pm
I happened on the drag coefficients for the various versions of the Evoque, and was surprised to discover that the five-door is marginally more 'slippery' than the Coupe (0.35 versus 0.36). I'd have thought the lower and ostensibly sleeker Coupe would have had the edge.
Theoretically, same-engined five-doors should be a tad more fuel efficient!
RE: Drag coefficient - smayo - 09-05-2012 01:59pm
Donny Dog, did the info you found give any difference for the Dynamic with it's little rear spoiler?
Probably makes didly squat difference.
RE: Drag coefficient - PhilSkill - 09-05-2012 02:04pm
Intriguing it's better, must be an effect of the sloped back roof? , 5dr is also 30kg heavier so probably cancels that out.
RE: Drag coefficient - Donny Dog - 09-05-2012 02:06pm
(09-05-2012 01:59pm)smayo Wrote: Donny Dog, did the info you found give any difference for the Dynamic with it's little rear spoiler?
Probably makes didly squat difference.
It didn't distinguish, it just gave drag coefficients for five-doors versus coupe.
(09-05-2012 02:04pm)PhilSkill Wrote: Intriguing it's better, must be an effect of the sloped back roof? , 5dr is also 30kg heavier so probably cancels that out.
Good point! Coupe drivers probably have heavier right feet, though, so maybe that cancels the rest out!!
RE: Drag coefficient - PhilSkill - 09-05-2012 02:28pm
Maybe those bonnet scoops on the Coupe cause drag!
Official MPG and 0-60 of 5dr and Coupe are identical.
Auto's are lower geared so has better accel, but lower top speed, unless lower top speed is part due to losses in the gearbox.
Makes me laugh TD4 and SD4 have identical MPG and yet have different 0-60 and top speed, Which shows the MPG figures are done using the same part of the mapping, which can't be using any of the improved power parts of the maps as they would require more fuel and thus worse mpg...
RE: Drag coefficient - Kimv - 09-05-2012 03:22pm
My vote is on the boundary layer detaching more easily due to the more sloped roof and thus inducing more drag
.This and:
Since: Drag Coefficient = (2F)/(pv²A) in which A = reference area.
One could conclude that the smaller the reference area, the higher the Drag Coefficient. For cars they use the projected frontal area as "A" btw...And I suppose that since the coupe is lower, the projected frontal area is smaller...
RE: Drag coefficient - pureevoque - 09-05-2012 05:18pm
That's what I was thinking !
RE: Drag coefficient - cjfp - 09-05-2012 05:22pm
I think it's because Coupe owners all have a larger grin that 5dr drivers ('cos they know they made the better choice) and hence more drag as the wind whistles past the teeth!
RE: Drag coefficient - Donny Dog - 09-05-2012 05:44pm
(09-05-2012 05:22pm)cjfp Wrote: I think it's because Coupe owners all have a larger grin that 5dr drivers ('cos they know they made the better choice) and hence more drag as the wind whistles past the teeth!
Higher smug coefficient, you mean?
RE: Drag coefficient - PhilSkill - 09-05-2012 08:28pm
(09-05-2012 03:22pm)Kimv Wrote: My vote is on the boundary layer detaching more easily due to the more sloped roof and thus inducing more drag
I'd go with that.
(09-05-2012 03:22pm)Kimv Wrote: This and:
Since: Drag Coefficient = (2F)/(pv²A) in which A = reference area.
One could conclude that the smaller the reference area, the higher the Drag Coefficient. For cars they use the projected frontal area as "A" btw...And I suppose that since the coupe is lower, the projected frontal area is smaller...
Now is the coupe lower... it tails off more at the rear, the front components are the same except bonnet, so maybe windscreen slope is not so high? Or does it start further forward and slope back more...?
Still it's irrelevant as the 5dr owners got to their destination while the coupe owners were waiting for their passenger to get in the back!