87 3.2 Carrera = 14.1 MPG in the city!?

[robotsex]

So I've had my 3.2 carrera for about a month now and been driving it pretty regularly. Calculated my MPG breakdown and currently I'm getting 14.1 MPG by my math with 75% city and 25% 60mph+ highway driving roughly. This MPG seems insanely low. I use 91 octane gasoline from Chevron, Shell, or Unocal. The car is stock except for the exhaust tip. At one point the previous owner had cat bypass, aftermarket exhaust, and a steve wong chip, which were all removed to pass smog. Since the car is new to me and I'm having fun driving it, my foot is probably heavy on the car, but even still seems very low MPG. It does currently have a K&N filter in it, which I have been urged to changed by many people on this board.

I'm taking the car in for service next week so I'll be sure to have them look into this. Any thoughts?

[MH911]

I've had my 87 since December and my over all gas mileage is 18.1, with a low of 14.9 and a high of 21.7. I'm also using 91 Octane mainly from Chevron. There is a even mix of city and country driving. Everything stock except for my Alpine.

I'll hit 90k tomorrow.

[steely]

I get 21 mostly highway (+80%) very consistent.
Around 15 mpg when I had her in the hills (blue ridge) over a few days - got over 24 cruising the turnpike once.

(monitored past 6K mi - turns 100K soon)
Had her 2 yrs. Did a lot of maintenance the first winter. (plugs, small vac lines, ign wires, cap, rotor, injctrs cleaned, new intake gaskets, fixed idle switch, cleaned throttle body, etc, etc, etc)

Can't say that my efforts made a big improvement.
BTW, a mech told me last week that I would not have passed the emissions requirement when she was in for state inspection. PA lets you waive it if you drive less than 5K miles and I just made it.
He said I would have probably passed with a Cat (see my sig block for more notes), had I required the emissions test.
I have no idea what effect this would have on the mpg.

Keep taking data, and doing minor maintenance and see what he recommends.

[Brando]

IMHO its due largely in part to Ethanol enriched gasoline, coupled with the slow, slow traffic in CA urban areas.

[PatrickB]

Is the o2 sensor connected? Get that SW CHip back in there!!!
I was getting close to 30mpg on the hwy with euro bypass, and SW Chip.
Staight city ~ 18mpg, mix ~23mpg
Make sure the brown wire is disconnected by the DME!
Also, no need to remove the SW chip for smog!

[g_vaxed]

fwiw, I've been getting an avg. of 20.2 mpg (50-50 hwy/city). Top end rebuild less than 3K miles ago, K&N filter & I'm a leadfoot. The currently additives in fuel is a concern as in the mid 90's the car got over 600+ hwy miles on a trip to FL (+/- 30mpg).

[dienstuhr]

Just did a 2K mile road trip with my '85 and calculated combined city/hwy was 26.8mpg...

[polizei]

+1 on replacing the O2 sensor - especially if you start to see any black residue on your bumper near the tail pipe. Ask me how I know And definitely get an SW chip - better throttle response and fuel economy!

[Hugh R]

SW Chip! and stay away from gas with ethanol, over time, it will eat up the rubber fuel lines. Union 76 (Unocal) uses ethanol. Stick with Chevron.

Someone told me with 10% ethanol, you get close to 10% less MPG, it's true. I ran a Mazda 626 for 5 years on ARCO and got 17-19 mpg, same driving switched to Chevron and over the next 5 years got consistently 21-23 mpg; about 10%

[JeremyD]

Bad o2 and/or cylinder head temp sender can screw up your mileage. My old 1987 3.2 used to get 18-20 in the city and up to 28 highway.

Even my 3.4 with higher compression and 993 cams got 15-16 in the city (but only about 10 on the track)

me thinks you have some sort of issue

[AlfonsoR]

I get from a low of 21.5 mpg with a fair amount of aggressive driving to a high of 25 mpg if I cruise at 75 mph indicated, which is more like 71 mph or so. This is about 60% hwy and 40% city.

Check your distributor, rotor, plugs and plug wires. As some have mentioned, a tune on these older cars DOES make a difference.

[m110]

I drive 20% freeway and live in LA, last tank was 20, andi have a bit of a lead foot....yours seems a little low. I have to try hard to get that low.

[stlrj]

Originally Posted by robotsex

Since the car is new to me and I'm having fun driving it, my foot is probably heavy on the car, but even still seems very low MPG.

I'm taking the car in for service next week so I'll be sure to have them look into this. Any thoughts?

You mean to tell me that you ignore the the upshift light that tells you when you should shift?


Cheers,

Joe

[Rot 911]

My '86 with 20K miles on a complete rebuild, SSI's, SW chip and Dansk 2-in 2-out gets 21mpg in town and 29mpg on the highway.

[brads911sc]

Hugh,

I use exclusively Chevron and it too has 10% Ethanol.

Just an FYI. Unless you buy Race fuel, you are probably getting Ethanol.

Originally Posted by Hugh R

SW Chip! and stay away from gas with ethanol, over time, it will eat up the rubber fuel lines. Union 76 (Unocal) uses ethanol. Stick with Chevron.

Someone told me with 10% ethanol, you get close to 10% less MPG, it's true. I ran a Mazda 626 for 5 years on ARCO and got 17-19 mpg, same driving switched to Chevron and over the next 5 years got consistently 21-23 mpg; about 10%

[Drisump]

Originally Posted by dienstuhr

Just did a 2K mile road trip with my '85 and calculated combined city/hwy was 26.8mpg...

Sorry man, is that Imperial or American gallons?I just have to tell our American friends that our Canadian gallon is 160oz not 128oz..... don't want you guys saying "whats wrong with my ride?" I have got as little as 14 mp(imperial) gallon at a track and as much as 33 on the hiway in my 85 Euro. If you are actually USING all the HP that your car can put out, ALL the time (ie. foot on the floor and never coasting) these cars are fully capable of using quite a lot of fuel. On the California coast hiway this spring, I ran out of gas at 547 miles..... wasn't looking at the tripometer, only at the fuel guage.... which I found out doesn't register under a quarter. So that incident indicates a 24.5 mp American gallon (547 divided by 22.5). Cheers P.S. My odometer and speedo are bang on.... weird eh?

[McLovin]

Originally Posted by Hugh R

SW Chip! and stay away from gas with ethanol, over time, it will eat up the rubber fuel lines. Union 76 (Unocal) uses ethanol. Stick with Chevron.

You live in California, right?

I agree with you on the harm of ethanol, but on that Chevron thing, I hate to break it to you . . . .

Anyways, as far as gas mileage, it depends on what "in town" driving exactly means. 14 mpg isn't unusual. Sitting at a light you are getting zero MPG, accelerating away from the light, even gently, gets very low mpg. True "city" driving, with lots of starts and stops, chews through fuel.

[tharbert]

We simply cannot get non-ethanol gas here in So. Ill. anymore. My one local station that offered 91 octane non-ethanol stopped selling premium altogether about a year ago. I think the only place left you can get it is at a marina with an outrageous mark-up.

It was certainly worth going out of the way to get the non-ethanol gas as I experienced about 15% drop in mileage havng to use alcohol blended gasoline.

[rusnak]

You guys with Steve Wong chips are getting better mileage than stock, and this is WITH the bridge to ground overrun disconnected? I find this hard to believe. Does anyone have hard numbers on this?

[jasonlee]

a little off topic, but here in Vancouver BC, Chevron 94 octane is the only fuel without ethanol, anything from 87-92 has a sticker that says may contain up to 10% ethanol.

That said, cat bypass, heavy foot, and I average about 22-25mpg highway/city. Albeit in an SC