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efedor

How many MPG are you getting from your Boxster?

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FWIW, I've been keeping a running total on my 2001 2.7 whenever I fill up, and I've gotten between 20 and 22.8 MPG each time. Of course, most of my mileage is either city or, uh, enthusiastic. :D

2000 2.7 gets 27 on highway and 1.1 at the track.

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Ok haters, the manual for the 04 says it has a 17 gallon tank so redo your math. I have a de snorkeled and KandN airfilter as well as NO cats. 5 speed,Top up,windows up with an occasional A/C here and there but not more than 15-20 minutes worth of use. No passengers, gas needle was slightly above the orange/red empty line. no luggage I even took a dump prior to that!

Using the calculator method, actual mileage divided by the number of gallons put in the tank, I've had 30.2 MPG on a trip to the southern part of the State. Drove about 185 miles with a wonderful speed limit of 50 here in Vermont. I must admit I did not drive aggressively at all, just a nice easy drive. Daily driving to work and back about 20 miles each way, I'm averaging 25 MPG.

With that said, I'm wondering why did you remove the cats? I realize you get a little more power but what about our environment? Does TX not have emission testing? Now I'm not a tree hugger by any means. Heck between all our toys my wife and I have 11 motorized vehicles needing registration. That's 4 cars, 2 motorcycles, 3 snowmobiles, 1 ATV and 1 boat. But I'd never purposely [and illegally] remove a critical emission controlling component.

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The biggest reason why I removed them was for performance. The way I had them done would allow me to slip the cats back in place before an emission test. I never gave the environment any thought, does that make me a bad person? As far as performance is concerned it was worth it the best mod I ever made.

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Here in Philadelphia, my 2.5L 986 gets anywhere from 17 to 21 mpg city. Highway I usually get 23-25. Made a trip 4 hours up to upstate NY, roof off, no cruise, no a/c, nighttime 55 degrees or so, doing 85-90mph, got 25mpg. I thought "not bad."

On the way back, sunny 65 degrees, roof off (windows up about half the time), no a/c, cruise control set at 73mph, one 10 minute burst of 120mph just to keep a TT behind me, and ended up with 28mpg! That's a record for me. I wonder what it would've been had I kept the roof on and drove the 65mph limit. But who are we kidding, we're Boxster owners!

Edited by fdmbautista

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On my 5 spd, 02 2.7 I get 29-30 mpg on the highway, 22 in town. I drive with a little spirit but not with stupidity. I am very happy with the mileage.

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I get 10 - 15 MPG around town, but I think my kids are siphoning my gas for their cars.

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I once got just under 700 km (what's that, 450 miles?) on a tank of 93 octane. It was just after I got the car, so fresh oil change, tire pressures perfect, and yes, western Ontario to Montreal is technically down-hill all the way. :-)

I can barely squeek 400 km out of the thing in the city with snow tires. Not so hot. Glad the summer wheels are back on.

Cheers!

P.S. And someone was bashing the Saabs... I got 1000 km out of a full tank of 93 octane on my 99 9-3, same "downhill" trip...

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I average 22 - 25 MPG, mixed City/ HWY. Long trips will go closer to 28. I have seen 29.5.

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Boxster S 2005, 3.2, 6 speed M, US, 17mpg.

I record 256m between yellow lights up, and divided by the premium I toped in. 17mpg.

I drived not crizy, but like a Boxster driver. I think I have responsibility to make the Boxster run and turn like a Boxster-need to smell ruber when you returned into garage, normally ram between 3k-4k, and occationally below 6k. no long run on high way.

oh, all stock, dealer oil change every year. Can't figure out how to get 20+ mpg

:)

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Update: I just took my first extended highway trip, and got 27-28MPG, mostly cruise control at 75 GPS MPH.

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From St. Cloud to the Twin Cities, 100 miles around Mpls, much in thick traffic, then more highway driving... 271 miles total, 10.63 gallons of gas, 25.5 mpg overall. That piqued my curiosity, as I'd expected something much worse, so I filled again after getting home, and that was 83 miles on 2.68 gallons of gas = 31mpg at 70mph on the highway.

This is 'vette territory for mileage, and I'm thrilled with the '03 Box S in this regard. The '02 standard Boxster that I had never pulled 30 on the highway.

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Mine gets the best milage out of any car in the garage.

01 Jeep Grand Cherokee LTD 31" AT/3" Lift/K&N 13.1.

05 John Cooper Works Mini Cooper S 30 MPG

00 Porsche Boxster S Super Charged among a whole long list of mods.. 34MPG HWY (When I keep my foot out of it so like twice per year)

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Just thought I would add to this, I can normally get 35mpg out of my boxster S when cruising down the motorway at around 65 - 70mph, with cruise control on and if I reset the MPG gauge once Im cruising. The minute I come off the motorway and in to urban driving I drop massively to down to around 18 - 22 MPG.

You can also get the mpg gauge to read 99.9 mpg by getting up to motorway speed, reset the mpg gause and take your foot off the throttle, it must confuse the engine management system.

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You can also get the mpg gauge to read 99.9 mpg by getting up to motorway speed, reset the mpg gause and take your foot off the throttle, it must confuse the engine management system.

Giving out my secret.

Here I am. 186 mph and the engine is not even running.

post-4-1211135660_thumb.jpg

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You can also get the mpg gauge to read 99.9 mpg by getting up to motorway speed, reset the mpg gause and take your foot off the throttle, it must confuse the engine management system.

Giving out my secret.

Here I am. 186 mph and the engine is not even running.

Opps, Tool Pants, Im sorry on that one :huh:

Love the pic, haha

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I'm going touring round Europe, so I was looking for easy to fit fuel economy mods for my 1999 2.5. I started by fitting new O2 sensors and MAF (as the ones fitted looked original and it has done 140k miles). Also the usual replacement higher flow stainless exhaust and de-snorkel had been done. I'm now trying water-doping (this is the cheaper, less complicated and more fuel efficient version of water injection). For the initial testing I have mounted the water reservoir where the US cars have the aux air system (right hand side of the engine bay), the vacuum diffuser is inserted into the engine breather pipe (from the air/oil separator) and the mist heater/gas reactor is clamped to the right-hand exhaust pipe next to the O2 sensor (see pictures).

 

05062016(001).jpg

05062016(002).jpg

 

The first fuel refill check showed an average of 31 mpg (UK gallon), this was for mixed driving (including motorways, city driving, traffic jams and some short journeys where the engine did not get up to temperature), also the water doping device was not installed for the first 50 miles of the tank of fuel. The fuel economy improvement is about 10% and the car feels nicer to drive too. The current installation requires an engine cover lift to refill the water reservoir, so if the economy improves sufficiently and I decide to keep it installed I will make a remote fill system to save lifting the cover.

 

If there is interest in water doping of Boxster engines I am happy to post my touring fuel consumption figures in about one month - let me know accordingly.

 

Update 29 July 2016 - We have just calculated the French trip mpg for the Boxster 2.5 fitted with the water doping system shown above, over 2736 miles (two people and full of luggage, with speeds of up to 130kph) the average mpg was 33.45. The anti-stall and idling seems smoother too, so we wonder if the steam has helped to de-carbonise the idle control valve. Encouraged by this we have designed and installed a new configuration with custom alloy bubbler (looks better than the plastic one), added a remote filling reservoir (so it is easy to top up - next to dipstick) and it now has twin mist heater/gas reactors. It now feels even better to drive (more responsive and more low down torque), so we are expecting even better results.

I agree with the comment below about not buying a Boxster S for fuel economy, but the Silverstone journey sounds like a very good economy drive. The 1999 Boxster 2.5 is my daily drive, it also has high miles (and cable throttle), so is not a refined as later models in terms of fuelling and economy. I am happy to save fuel and enjoy the car daily without such a big dent in the wallet for petrol when it can be saved cheaply with no detriment. BTW I do all my own maintenance and am prepared to experiment, this sort of project may not suit others. If anyone would like details of the updated installation and long term average fuel economy let me know.

Edited by battery.burner
Results added

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2003 Boxster 986 S, drove from South Wales to Silverstone and back to South Wales, 70mph on the motorway with the roof down, had 31mpg average. Always filled up with high octane fuel, tyre pressure even, etc. That's with driving super carefully around towns as well though. Anything else and it starts to drop quite drastically lol.

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On 6/12/2016 at 10:06 AM, battery.burner said:

If anyone would like details of the updated installation and long term average fuel economy let me know.

 

I guess I have been living under a rock because I've never heard of "water doping" an engine before.  It sounds like something that will get my car thrown out of the Olympics.  And, if it really improves gas millage then why don't modern car manufacturers do it?  Oil industry conspiracy?   Sounds a lot like the people that promote converting your car to running on gas vapors instead of liquid gas - it will by the way but just doesn't get you any better gas mileage.    

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Did not buy my 03 Boxster S for gas mileage.....:-P
Ditto.....


Sent from my SM-G930T using Tapatalk

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On the highway at non-felony speeds I get 28mpg, which I think is a couple better than EPA quoted. All other driving I get the biggest smiles per tank full !! . . . and mine is a "slow" one.

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