Whats your MPG?

whiterabbit · Post by **whiterabbit** » Mon Jun 06, 2011 4:51 pm

81 IF Spider bone stock,13"rims=20mpg. Finally went through two tanks of gas and it came out to around 20. New plugs,wires and vac advance on dizzy. Is that average or low? I was hoping for mid to upper 20's.

Snoopy · Post by **Snoopy** » Mon Jun 06, 2011 5:18 pm

TX82FIAT · Post by **TX82FIAT** » Mon Jun 06, 2011 6:55 pm

I recently used the GPS and the tank size to calculate mpg on a drive from Dallas to San Antonio. 4000 RPM's the entire trip and came out to 26 MPG. Made the trip in just under a tank.

aj81spider · Post by **aj81spider** » Mon Jun 06, 2011 6:56 pm

I have an 81 FI that gets a mix of highway and country road driving. Average MPG is 23-24.

Redline · Post by **Redline** » Tue Jun 07, 2011 7:16 am

27 mpg (US) average over the last year ('71 Coupe, 1608, dual carbs)

124ADDHE · Post by **124ADDHE** » Tue Jun 07, 2011 9:40 am

I average just over 32mpg with the dual carbs and electronic igntion on the 1.8 w/ 3.90 rear end going nice and gentle on the way to town (little hill, few 90's and no stop signs @ 100kmph)...have some fun and I am looking at about 20-22 in the twisties.

DUCeditor · Post by **DUCeditor** » Tue Jun 07, 2011 12:35 pm

1977 1800. 26 MPG average, almost all back roads.

-don

baltobernie · Post by **baltobernie** » Tue Jun 07, 2011 2:22 pm

Modified 1800. 20-22 MPG city or highway; doesn't seem to matter.

grittracing · Post by **grittracing** » Tue Jun 07, 2011 4:07 pm

i figured mine out around 22mpg put im still fighting a fixture issue. Running rich.

sptcoupe · Post by **sptcoupe** » Tue Jun 07, 2011 4:42 pm

Our 81 spider gets about 25-26 on the hiway, about 23-23 around town. Stock except for a header and K&N intake. Drove the coupe with its new 2.0L, highly modified engine with 44 IDFs for a good while this weekend. Very heavy footed, but got about 19 mpg. On other, similarly built 2.0L units I got about 24 hiway, if gentle. The Prima 500 has posted 37.1 for the first 4560 miles. On a 100% freeway drive with the speed control at 72, I got 41.3 over 295 miles. On the current tank, after 255 "daily driver" miles, I am getting 38.2, but I have been trying to really maximize mileage on this tank to see what it is capable of, so it is not a realistic number (at least for me), as I am missing way too much fun! I noticed the mileage improved after about 3000 miles. I have twice checked the mileage manually, and it seems the computer reports about .1 miles more per gallon than the I calculated, which is essentially no difference..

whiterabbit · Post by **whiterabbit** » Tue Jun 07, 2011 11:56 pm

Hmmmmm. Igott'a tune mine up better! I think after a frt end alignment and better exhaust it should go up. All you can find around here is that crappy 10 % ethanol gas.

boogiedude · Post by **boogiedude** » Wed Jun 08, 2011 12:05 am

I get about 19-20 if I'm semi conservative with mine. 78 1800, essentially stock with emissions eliminated, and early 4-2-1 manifold, and 38adl carb. Used to get 22-23 before I switched off the stock carb.

I also have a lot of gas smell in my car along with a lot of mountain driving

Redline · Post by **Redline** » Tue Aug 02, 2011 3:47 am

Redline wrote:27 mpg (US) average over the last year ('71 Coupe, 1608, dual carbs)

A small update, as I had the dual carbs cleaned and rebuilt (apparently they were quite full of varnish).

1st tank after the rebuild: 7.9 l/100km (30 USmpg)
2nd tank after the rebuild: 6.9 l/100km (34 USmpg)

That's in mixed daily driving and often making those dual Webers sing like the trumpets of Jericho. Who would have ever imagined that Lampredi's mechanical marvel, coupled to a psychotic gear box, driving 205 rubber, would make a good economy car.

SouthSwedeSpider · Post by **SouthSwedeSpider** » Tue Aug 02, 2011 8:04 am

1980 stock FI, recently rebuilt head, no cat. I get around 31 US mpg when driving mainly at highways and countryside roads , with some urban driving and some occational

overtaking. Quite satisfied with that. Dont think I've ever been below 25 mpg, maybe I'm driving too gently...

dom · Post by **dom** » Tue Aug 02, 2011 9:35 am

I read somewhere that the dual car setup will improve your MPG on the highway compared to single carb setup but in the city MPG goes down. With the twin carbs when idling or low revs fuel is being wasted but on the highway it is a more efficient set up.

Redline wrote:
Redline wrote:27 mpg (US) average over the last year ('71 Coupe, 1608, dual carbs)
A small update, as I had the dual carbs cleaned and rebuilt (apparently they were quite full of varnish).

1st tank after the rebuild: 7.9 l/100km (30 USmpg)
2nd tank after the rebuild: 6.9 l/100km (34 USmpg)

That's in mixed daily driving and often making those dual Webers sing like the trumpets of Jericho. Who would have ever imagined that Lampredi's mechanical marvel, coupled to a psychotic gear box, driving 205 rubber, would make a good economy car.

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