MPG to expect?

[FestivaBob]

I picked up a 90 FI 5 spd almost 2 years ago, because it was $300, needed a muffler, tstat, and axle.

I set it in a field until my Civic hatch needed a repair last month. I ran the Festy a few times a month, to keep the nasties out.

Anyway, MPG has been increasing every tank, as I change the oil (old stuff had reverted to about a 20w), get round tires, remove junk/weight/dirt.

I am up to 38.5 combined on the last two tanks, one on 93, one on 87. My 1.3L Civic was at 44 before vac leaks.

What can I expect as a best case scenario with this Festy? Where should I look to improve this cars effiency?

Thanks,
Bob

[pyrothehitman]

38.5 is pretty good. i think they can get up to 48mpg. and i heard reports of it in the 50's.

everything takes a factor in mpg...from open windows to tire pressure....to city vs highway driving..to how you drive stick.

[TominMO]

Your combined mileage is good, so it seems the car is running right. You should be able to hit 50 MPG pretty easily on the hwy, if you keep the speed to 60 MPH or so. Dropping to 55 MPH makes a big difference too. At 45 MPH in fifth I got 62.5 MPG, on an 85-mile test loop.

Various factors:
tighten down the nut behind the wheel (most important factor)
properly operating O2 sensor and MAF
unclogged cat
rear brakes and wheel bearings not dragging
recent tuneup--air filter, plugs, wires, cap & rotor
toss a bottle of STP Fuel System Cleaner into the gas tank
windows and tire pressure, as Pyro stated
tire width and height--recommend 155/80x13s (on JY Metro steelies) for best mileage
the weight of tires/wheels (affects city driving mainly)

[Darlo]

Well I think my LOWEST tank was 41.5 mpg (could check by clicking my Fuelly tag below, lol)

My highest tank was over 51mpg

My average in the summer is 48mpg, and in the winter (with studded winter tires) is 44mpg.

I drive like a granny (aka I drive the speed limit or less, lol)

[jamesmc]

You can get 50mpg easily on the highway, but realistically I'd except 40-45. There aren't many modifications you can do to improve that. Make sure your tire pressure is sufficient. On a long trip, I had mine at 45psi. As stated above, lowering your highway speeds can have a significant impact. But try to keep your speed at a safe level. Don't go 55 if everyone around you is going 90. :p Take it easy and try to waste less momentum. Not only will you save money at the pump, you won't have to replace your brakes as often.

[Pu241]

Not bad for not being driven in 2 years.
Might want to stick with 87,89, or premium just to hold a variable constant,
while you continue to make changes that hopefully positively impact MPG.
Join Fuelly.com will also help you compare your performance to others.
But, this is no substitute for keeping a fuel and repair log in the car.

Things to check:
max tire pressure
brakes not dragging
bearings good
coast when you can
do not idle excessively or at all if you can help it
Block upper grill (I currently run both an upper and lower grill block)

Others will also have other suggestions.
But most significant has already been mentioned slow down

[Darlo]

Yes indeed!

The air drag equation is as follows:

F = Cd * rho * A * V^2

Cd = drag coefficient (you can change this with mods like a Kamm back, lowering the car etc)

rho = Density of the air (you cant change this, lol)

A = frontal area of the car (not much you can do to lower this unless you remove your mirror(s), or take a sledge hammer to your roof, lol)

V^2 = velocity SQUARED! meaning that if you drive 10% faster, your drag increases by 21% (1.1^2 = 1.21). Looking at this a different way, if you are able to drive slower, your savings will me squared, lol........You start to see this BIG TIME if you drive 75mph in a 55mph zone, as this is 36.3% faster which translates to an 86% increase in drag!

A couple of cool resources:

http://en.wikipedia.org/wiki/Automobile_drag_coefficient

http://ecomodder.com/forum/fuel-economy-mpg-modifications.php

[georgeb]

40 MPGs is the benchmark I use to determine if something is amiss or not. Have gotten as high as 46 in my carbed 4-speed.

[FestivaBob]

OK. I thought 38ish nmight be a bit amiss, but doesn't sound too bad. I drive 65 behind whatever big arse vehicle I can find, Rarely exceed 1/2 throttle, and aim to be in 5th by 30 mph. I have lower air pressure (30psi) in my 12" tires now, prepped for winter that never came. Has anyone bored out the "hub hole" in a Honda wheel to fit it on a Festy? 13s fal from the sky for Hondas. I'm assuming the increase in dia. reduces the final drive ratio for the mpg increase?

BTW, holy torque! 28 mph, 7% grade, 4th gear and I was accelerating!

[blackhandbeagles]

I just replaced my old 1.3 in a 93 festy with an Aspire 1.3. On the old engine I was getting 38 mpg in the winter and 42 mpg in the summer. This is combined driving with about 60% hw miles.

I just ran my second tank through and got just under 40 mpg, and that included more back country roads than normal. I run between 70-75 highway and live in the hills of eastern Ohio.

[blackhandbeagles]

BTW, FestivaBob, I work downtown Columbus. I have some parts sources for when you need them.

[FestivaBob]

WooHoo! solid.