MPG's w/ the top down

So I am sure it has been discussed multiple times, but what type of mpg drop are you seeing when driving primary with the top down. Right now w/ my 2003 986, I am looking at about 5 mpg's. Now keep in mind I dont have the rear wind stop.

What does everyone else experience? Does the rear wind stop make a huge difference?

Regards

Well yes, just curious. I am the son of an engineer lol

The windstop will give you at least an extra 6 MPG.

I doubt that there's any difference around town, but on the highway I might get a couple more MPG. I haven't really had a chance to try it since I enjoy being a topless driver and seldomly have the top up. Don't need no stinkin' roof when you've got the sun overhead and that sweet flat six singing in your ear.

Well its more than just curiosity, I am getting about 21 mpg's when driving primarily with the top down. That seems really loooooow. I'm just trying to eliminate potential issues.

But, as everyone has accurately pointed out, who cares? I'm driving around with the top down in the beautiful North Carolina weather.

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mnchstrcityblues79
Well its more than just curiosity, I am getting about 21 mpg's when driving primarily with the top down. That seems really loooooow. I'm just trying to eliminate potential issues.

But, as everyone has accurately pointed out, who cares? I'm driving around with the top down in the beautiful North Carolina weather.

You are lucky. We just drove through NC last weekend on our way home from Florida. We had the sunroof open that whole stretch.

With my '06, five speed, I get between 28 and 32 mpg on staight highway runs with top down.

...now when I get into those curvey roads in the NC mountains, mileage does tend to fall off somewhat. BRBS. Can't wait.



Edited 1 time(s). Last edit at 04/16/2012 11:10PM by Guenter in Ontario. (view changes)

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Guenter in Ontario

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mnchstrcityblues79
Well its more than just curiosity, I am getting about 21 mpg's when driving primarily with the top down. That seems really loooooow. I'm just trying to eliminate potential issues.

But, as everyone has accurately pointed out, who cares? I'm driving around with the top down in the beautiful North Carolina weather.

You are lucky. We just drove through NC last weekend on our way home from Florida. We had the sunroof open that whole stretch.

With my '06, five speed, I get between 28 and 32 mpg on staight highway runs with top down.

...now when I get into those curvey roads in the NC mountains, mileage does tend to fall off somewhat. BRBS. Can't wait.

Wait, what? 28 to 32?? Jeez, next question, whats wrong with my Boxster? I don't think I've ever owned a Boxster that got that mileage (though I've never owned a Boxster that was less than 5 years old)

Where do you keep your Tach? Ill be honest, I keep mine at around 4k for a number of reasons. 1) I love the sound, 2) I love the response and 3) I have an irrational fear of lugging the engine and thus causing a IMS failure lol

Keeping the revs up impacts gas mileage significantly. Cruising down the highway in top gear with the engine running below 2500 RPM is the best gas mileage. Keeping the RPMs between 4500 and 6500 on the track with no coasting (either on gas or brake) gets me single digit MPG in my 03.

Keep the car tuned, air filter, oil filter and oil changed. Put the top down, head to those N.C. hills and enjoy the car. Many here envy you for your good fortune of living in North Carolina!

Dave - 06 987 S coupe SG/NL; gone (but still my first love): 03 986 AS/GG/BK;

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mnchstrcityblues79

Wait, what? 28 to 32?? Jeez, next question, whats wrong with my Boxster? I don't think I've ever owned a Boxster that got that mileage (though I've never owned a Boxster that was less than 5 years old)

Where do you keep your Tach? Ill be honest, I keep mine at around 4k for a number of reasons. 1) I love the sound, 2) I love the response and 3) I have an irrational fear of lugging the engine and thus causing a IMS failure lol

Remember, that's straight highway runs at 28 - 32 mpg. That's cuising in 5th at a steady 70 and err slightly above mph so the tach will be sitting around the 3 k mark. As soon as you get into any city traffic or twisties and start conducting the orchestra vigorously, mileage will drop. Driving in the NC mountains with ...umm enthusiasm , (not likely to get past 3rd gear), mileage drops to around 24 mpg. Straight city traffic will be more in the 21 - 23 mpg range or even less if there's a lot of stop and go.

Guenter
2014 Boxster S
GT Silver, 6 Speed Manual, Bi-Xenons, Sports Suspension (lowers car 20mm), Porsche Sports Exhaust, Porsche Torque Vectoring, Auto Climate control, heated and vented seats, 20" Carrera S Wheels, Pedro's TechNoWind, Sport Design steering wheel, Roll bars in GT Silver
[www.cyberdesignconcepts.com]

agree. The RPMs have a huge roll. At 4K you are driving about 1500 RPM more than in top gear on the highway. My 997S can get 27 or 28 mpg (70-75 mph) on the highway in seventh gear (PDK). If I kick that up to 80-90 mph, it's more like around 24 to 25 mpgs. Haven't done it with the top down. Areodynamics would be impacted, so maybe more drag would slightly reduce the mpg, but wouldn't imagine much.

The one time I took my 997S on the track, with the top up, I reset the OBC and got 9 mpg. So, driving around at 4k RPM is going to eat much more gas. Same thing with how fast you start from stop signs/lights or stomping on the gas to pass slower cars. That'll all eat more gas. I even get better gas mileage without speed control as I can make slight gas pedal adjustments based on the terrain ahead, instead of the computer hitting the gas hard because of slowing down going up a hill. Smooth and controlled will always get you better MPGs, rolling to a stop, etc., too. That's how race car drivers win those "fuel mileage" races.

I'm surprised you didn't ask for both top up and top down mpg. There is a wide variation in fuel economy different people on this forum get. Getting just the top down numbers doesn't tell you much.

FWIW, my mileage top up or down is not noticeably different.

Great stuff guys, thanks. No worries about IMS issues and low RPMS?

..so who would care?

Agree there are so many other variables you must compare w/ and w/o same conditions

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

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Boxsterra

FWIW, my mileage top up or down is not noticeably different.

Since you're rarely under 4,000 RPM, I'm not surprised

So what I need to take from here is use 5th gear? Lol

No, stay in third gear and don't sweat the little stuff like fuel economy or mythical IMS issues.

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Gary in SoFL
No, stay in third gear and don't sweat the little stuff like fuel economy or mythical IMS issues.

Very helpful post, thank you.

it helps your IMS. Then you read that cars with TIP rarely have IMS issues, my 986 TIP hardly goes over 2k unless I am on the highway. I'm with Gary on this, enjoy the ride.

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Naples986
it helps your IMS. Then you read that cars with TIP rarely have IMS issues, my 986 TIP hardly goes over 2k unless I am on the highway. I'm with Gary on this, enjoy the ride.

No TIP on my ride.

And yes, to address everyone's concern, regardless of MPG, I intend to enjoy the ride.

or so i have heard. Yes, all keep in mind that to 95% of the porsche public IMS and RMS are either interchangeable or indistinguishable.

So beware what you hear.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

IIRC the notion that there is a difference in the TIP/Manual frequencies in favor if the TIP dates back almost to the original discussions of the problem people were seeing. Those who originally thought that have since acquired more samples/data and no longer think a TIP is better and in fact think the low speed most TIPs rev at is a negative and contributing factor.

memory of when I did drive it this way and checked the mpg the mpg was unaffected. That is the numbers were so close to the top up numbers I couldn't tell from the numbers if the top was up or down.

The bigger variable is how you drive, and how fast you drive. In fact with the top down you might drive slower and mpg improves.

The wind stop didn't catch any wind, the wind flow was over the cabin and over the wind stop.

In fact a couple of times I drove with the top down in light rain without getting wet or any water in the cabin, but not for long cause I'd chicken out because I usually was not sure I could keep moving so as soon as I could I'd pull in somewhere with some protection from the rain -- gas station with covered pump islands -- and raise the top.

Oh, I usually drove with the side windows up. If you drive with them down mpg might be affected -- it can be with the top up -- or you might get wet if you drive in the rain..

Sincerely,

MarcW.

I typically get 42 on the highway with top up, 37 with windstop (consistent 5MPG improvement), 26 without. But I have one of those cool mpg devices:

[www.ebay.com]

BTW. Just kidding. Don't buy one!

Wow, a two for one offer!

P. T. Barnum would be proud.

Dave - 06 987 S coupe SG/NL; gone (but still my first love): 03 986 AS/GG/BK;

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kosiba
BTW. Just kidding. Don't buy one!

Dangnabit! I was wanting to buy one but they didn't have one listed for a Porsche.

It's a real shame because each one is so carefully custom designed for each individual car.

Guenter
2014 Boxster S
GT Silver, 6 Speed Manual, Bi-Xenons, Sports Suspension (lowers car 20mm), Porsche Sports Exhaust, Porsche Torque Vectoring, Auto Climate control, heated and vented seats, 20" Carrera S Wheels, Pedro's TechNoWind, Sport Design steering wheel, Roll bars in GT Silver
[www.cyberdesignconcepts.com]

I've done this experiment a couple of times: the difference for me between top up and top down on a long highway drive has been about 2-3mpg. This was as true for my 2003 986 as it is for my current 987.5.

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AS2003
I've done this experiment a couple of times: the difference for me between top up and top down on a long highway drive has been about 2-3mpg. This was as true for my 2003 986 as it is for my current 987.5.

Thank you very much for your post. It doesn't exactly comport with my experience but when you factor in my 4k+ approach, I think I know where my mpgs are going

That is a bunch of BS, AS2003. How can you get fewer MPG when the top is down!?! Clearly the top weighs 30-50 pounds, and when you remove that extra weight with the top down your mileage would go UP, not down.

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kosiba
That is a bunch of BS, AS2003. How can you get fewer MPG when the top is down!?! Clearly the top weighs 30-50 pounds, and when you remove that extra weight with the top down your mileage would go UP, not down.

You're kidding, right?

Edited 1 time(s). Last edit at 04/19/2012 04:05PM by kosiba. (view changes)

Edited 1 time(s). Last edit at 04/19/2012 04:05PM by kosiba. (view changes)

But top down should help the air conditioners run easier. When the buildup of cabin pressure gets too high, the fans have to push harder and harder.

Also, if you drive too long with the fans (especially the defroster) going full-bore, it could increase the pressure in the cabin so the tops may "pop" and buckle. I'd expect that would be expensive to fix.

Best practice is to crack the windows every 5 minutes or so to relieve the pressure or to drive top down. Heaven help you if there is a cabin explosion.

Come to think of it, isn't it funny that Porsche decided to put in glass rear windows? Ever hear of the plastic cracking? Ever wonder why?

Edited 1 time(s). Last edit at 04/19/2012 04:47PM by Laz. (view changes)

Most important - make sure it's mounted downstream of the air filter, so when the blades fall off, they will be ingested by the engine, and fuel economy will never be a worry again...

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kosiba
I typically get 42 on the highway with top up, 37 with windstop (consistent 5MPG improvement), 26 without. But I have one of those cool mpg devices:

Wow! You got one too? Your installation must be slightly more effecient than mine.

G-man, shouldn't that be kilometer per liter on CURVEN8R?

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jwdbox
G-man, shouldn't that be kilometer per liter on CURVEN8R?

Well kind of sort of.

Normally, I have fuel consumption set to read liters per 100 kilometers ( l/100km ) which is the metric version of measurement of fuel consumption, where you measure how many liters the car consumes every 100 km driven. So that 41.4 mpg would be about 5.6 l/100km.

This picture was taken between Flagstaff, AZ and Sedona. Whenever we're travelling in the US, I change all the OBC measurements to US measurements - Farenheit, miles, mpg. I had filled it in Flagstaff (I always reset all OBC readings to 0 at a fillup) and a good part of the distance (27.3 miles) had been downhill, stuck behind a van on 89A. This mileage was the result. When I saw it, I just had to pull over (I couldn't drive that fast behind the van anyway ) and recorded this mileage.

I only wish I could get 41 kilometers per liter. That would convert to about 95 mpg