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Aerodynamic drag and why a coupe is better

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
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Smartbear
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Aerodynamic drag and why a coupe is better

Post by Smartbear » Tue Sep 08, 2020 6:38 pm

MACK wrote: Tue Sep 08, 2020 6:09 pm Getting back on top kinda.
I was always told using the air con had a detrimental effect on fuel economy. Obviously driving top down isn't as efficient as top up, but I do wonder how top down and air con off compares with top up and air con on.
I read that driving with the windows down was worse for economy than driving with the ac on, I should think that top down driving’s far worse than just windows down :?
Rob
Last edited by Smartbear on Tue Sep 08, 2020 10:34 pm, edited 1 time in total.
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e89 Sdrive 20i, plenty of mumbo & good economy-the thinking bears z4
e89 Sdrive 30i, this ones busted, pass me another...
e85 3.0si sold

Pbondar

Aerodynamic drag and why a coupe is better

Post by Pbondar » Tue Sep 08, 2020 6:51 pm

At least 23% plus more drag according to this ..ish..
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flybobbie
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Aerodynamic drag and why a coupe is better

Post by flybobbie » Tue Sep 08, 2020 7:59 pm

I have driven everyday with the roof down, still get 29-30 mpg, half town and country. Same as roof up winter.
I would say quality of fuel is a factor, i noticed my car and bike didn't like the cheap £1.01 litre petrol from Asda..
I'm sticking to Shell unleaded and that runs better than the super.

(Looks like that instrument panel cost more than the aircraft, i'm just trying to solve a climb power problem on a Tomahawk).

Pbondar

Aerodynamic drag and why a coupe is better

Post by Pbondar » Tue Sep 08, 2020 10:22 pm

I get about 28mpg measured over 3,000 miles..and generally that’s a pretty rapid pace...with lots of acceleration and braking due to the nature of the roads where I potter ... :driving:

I probably spent around £25k avionics on a £66k build back in late 1990s on G-POOP.. IFR GPS..two other GPS plus 2 axis auto pilot didn’t help... :tumbleweed:

BadgerDog
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Aerodynamic drag and why a coupe is better

Post by BadgerDog » Wed Sep 09, 2020 6:33 am

I get... less mpg. The larger engine loves to chug gas if you are on and off the throttle. Not too bad cruising down a highway on cruise control, but whats the fun in that?

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Aerodynamic drag and why a coupe is better

Post by Busterboo » Thu Sep 10, 2020 1:09 am

Smartbear wrote: Tue Sep 08, 2020 6:38 pm I read that driving with the windows down was worse for economy than driving with the ac on, I should think that top down driving’s far worse than just windows down :?
Rob
A glue-on spoiler's worst. Especially on a yellow car. :wink:
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Aerodynamic drag and why a coupe is better

Post by BadgerDog » Thu Sep 10, 2020 6:28 am

Busterboo wrote: Thu Sep 10, 2020 1:09 am A glue-on spoiler's worst. Especially on a yellow car. :wink:
Whomever could you POSSIBLY be talking about hmmmm?

Pbondar

Aerodynamic drag and why a coupe is better

Post by Pbondar » Thu Sep 10, 2020 8:47 am

BadgerDog wrote: Thu Sep 10, 2020 6:28 am
Busterboo wrote: Thu Sep 10, 2020 1:09 am A glue-on spoiler's worst. Especially on a yellow car. :wink:
Whomever could you POSSIBLY be talking about hmmmm?
Well I love it...gives it a nice pert look..much like the E85s...the standard E89 bottom looks like a 60 year old grandma’s slightly overweight bum, especially in some of the bland colours.. :thumbsup:

I agree that non colour matched spoilers look really naff, and some look naff even colour matched.. :tumbleweed:

Judging by how many unprompted positive comments the car gets compared to other E89s the public seem to like it...

Now that Busterboo has been enlightened to switch off signature graphics he doesn’t need to use his dark sunglasses any more :thumbsup:

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Aerodynamic drag and why a coupe is better

Post by Busterboo » Thu Sep 10, 2020 9:39 am

Thrashed at least once a week, my 35iS did 26.4 mpg from 20k to 65k miles with few long runs and no commuting.

It then had a new battery and the figure fell immediately to 24.5. Now, at 70k miles, it's creeping over 26.0 again.
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mr wilks
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Aerodynamic drag and why a coupe is better

Post by mr wilks » Thu Sep 10, 2020 9:45 am

Pbondar wrote: Tue Sep 08, 2020 10:22 pm I get about 28mpg measured over 3,000 miles..and generally that’s a pretty rapid pace...with lots of acceleration and braking due to the nature of the roads where I potter ... :driving:
Your obc should also have the average speed over those miles :roll: bet its nearer 30mph than 60mph :wink:
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Pbondar

Aerodynamic drag and why a coupe is better

Post by Pbondar » Thu Sep 10, 2020 9:58 am

mr wilks wrote: Thu Sep 10, 2020 9:45 am
Pbondar wrote: Tue Sep 08, 2020 10:22 pm I get about 28mpg measured over 3,000 miles..and generally that’s a pretty rapid pace...with lots of acceleration and braking due to the nature of the roads where I potter ... :driving:
Your obc should also have the average speed over those miles :roll: bet its nearer 30mph than 60mph :wink:
Mr Wilks true ..41.3 mph ..

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Aerodynamic drag and why a coupe is better

Post by Busterboo » Thu Sep 10, 2020 10:10 am

Busterboo wrote: Thu Sep 10, 2020 9:39 am Thrashed at least once a week, my 35iS did 26.4 mpg from 20k to 65k miles with few long runs and no commuting.

It then had a new battery and the figure fell immediately to 24.5. Now, at 70k miles, it's creeping over 26.0 again.
All on 95RON, of course. :wink:
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Aerodynamic drag and why a coupe is better

Post by enuff_zed » Thu Sep 10, 2020 10:11 am

Busterboo wrote: Thu Sep 10, 2020 10:10 am
Busterboo wrote: Thu Sep 10, 2020 9:39 am Thrashed at least once a week, my 35iS did 26.4 mpg from 20k to 65k miles with few long runs and no commuting.

It then had a new battery and the figure fell immediately to 24.5. Now, at 70k miles, it's creeping over 26.0 again.
All on 95RON, of course. :wink:
So are you now telling us new batteries are heavier and gradually lose weight as you use them? :poke: :D
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Aerodynamic drag and why a coupe is better

Post by mcbutler » Thu Sep 10, 2020 10:38 am

Pbondar wrote: Tue Sep 08, 2020 3:37 pm
flybobbie wrote: Tue Sep 08, 2020 3:21 pm 3 and 4 looks a bit draughty in the back seats.
What kit plane did you get 155kts on 100hp, Pulsar by any chance.

I'm still waiting to try out a Glasair in the hanger.
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Aerodynamic drag and why a coupe is better

Post by Nictrix » Thu Sep 10, 2020 12:31 pm

enuff_zed wrote: Thu Sep 10, 2020 10:11 am
Busterboo wrote: Thu Sep 10, 2020 10:10 am
Busterboo wrote: Thu Sep 10, 2020 9:39 am Thrashed at least once a week, my 35iS did 26.4 mpg from 20k to 65k miles with few long runs and no commuting.

It then had a new battery and the figure fell immediately to 24.5. Now, at 70k miles, it's creeping over 26.0 again.
All on 95RON, of course. :wink:
So are you now telling us new batteries are heavier and gradually lose weight as you use them? :poke: :D
:lol: :lol:
E89 2014 35i M Sport Black with Black leather :)

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