1995 Honda Civic not so great highway mileage

[nasoj007]

Hi everyone,

I haven't been a member of this site for very long but I'm already hooked. There's a huge amount of helpful tips and tricks that range from mild to wild... it's great.

Anyway I have a '95 Civic DX automatic and I'm a little bothered by my highway mileage. Driving 98% of the time in the city I get 29 - 32 MPG but driving on the highway 95% of the time I only get 34 - 36 MPG. I drive at... umm gotta do the conversions in my head... 60-65ish mph, the AC's on most of the time but it is during the city driving too, and I don't tend to pass people or drive aggressively. I recently raised my tires pressure to 40psi just before the tank that I got 34+ MPG so I don't even know if the increase is the highway driving or the PSI increase...arrrg. I guess I'll find out after my next fill.

I don't want to resort to some of the more extreme hypermiling techniques out there like boat-tails or EOC but I've tried some Pulse and Glide and turning the engine off instead of long idling. The area I live in is very hilly and don't even get me started on the drivers, so EOC or even Pulse and Glide can be very difficult to do. If you slow down TO the posted speed limit you might get rammed let alone drop below the speed limit . I can coast almost the whole drive from my fiances place but the drive back is all up hill.

I didn't mean to write a novel here but if anyone else have a Civic with an automatice I'd like to here how you do on the highway (probably could have shortened the post considerably by starting with this question lol)?

Thanks.

[SVOboy]

Welcome to ecomodder! The culprit could indeed be the automatic, what kind of revs are you running?

[99metro]

If I drove like that, I would get about the same MPG as you. I took me a while to get used to getting passed all the time. I used to be the one doing the passing. Tailgaters will be tailgaters whether you are driving 50 mph or 200 mph.

If you could drop to 50-55 mph (80-88 kph), you'd probably get in the 40's. If you see cars coming up behind you, just hug the right line, or even a couple tire widths to the right of it to encourage them to pass. You might want to hit the hazards to give them fair warning ahead of time.

If you have lots of up and down hills, you can actually do very well if you drive them right. It takes patience and practice to acquire the skills, but it's doable. I pulse and glide on my little hills by pulsing on top of the hill to about 1/4 down, then gliding the middle half, then a little throttle for momentum the last 1/4 of the downhill pluse a tad up, then gradually decreasing throttle on the way up the next. On the long uphills, best to stay in Overdrive or 5th and steady throttle but slow speed all the way up. I haven't figured a better way yet. 3rd and 4th give the worst uphill economy, but 5th gives the best up hills.

I've been hypermiling two of my automatics lately, and have found a dramatic increase in economy by neutral coasting with the engine on (pulse and glide from 60mph down to 45mph, then 75% throttle back up to 60mph), super extended coasting in nuetral to the stop signs (at least 1/3 of a mile or .5km), and very slow (1 mile or 1.6km) accelerations from a stop to 55mph (88).

Everything is a work in progress and subject to improvements.

[Tourigjm]

my guess is your car has a 3 speed transmission (no overdrive)

Same situation i have, and if i drove 65 mph i would get a pretty consistent 32 mpg highway. P&G from 50-60-50 on the highway ups it to the high 40's, even though im N-ice on coasting.

[azraelswrd]

Indeed. Besides slowing down, can you reduce the AC usage? That takes a big hit on the fuel economy as well. Since you do so much highway driving, aero mods might also help.

[KJSatz]

(correct me) I think that even running the fan on the first click instead of like the third or fourth will help out with the fuel economy. You can also try aiming vents at your hands and/or face to make less AC more effective, or try turning it on for a few minutes, turning the fan off until you feel uncomfortable, and then running it on low again for a few minutes. That should curb the impact of AC to an extent.

[nasoj007]

Thanks for all the replies. The car does have a 4spd auto w/overdrive but the sweet spot seems to be around 55mph. I don't have a tach so an educated guess on the rpms at 65 are about 3000-3500ish. I usually run the AC on high until the car is cool and then turn it down to 1. Off isn't an option when my fiance is in the car and on the last half of my trip I did the cool the car down then turn the AC off, repeat when warm. I may try a few aero mods like grill blocks or a belly pan in the future but for now I'll try to improve my driving techniques.

P.S. What spark plugs do you guys recommend. I recently got a set of Bosch +4 platinums and I HATE them. I don't find they work as good as the worn out Champions that I took out. Plus how do you check the gap... it's nuts. Thanks again.

[SVOboy]

NGK is where it's at for spark plugs! Sounds like you need an mpguino

[Vince-HX]

honda's love Ngk spark plugs

damn, beat me to it, lol

+1 one the mpguino

[nasoj007]

You guys aren't the first to recommend the NGK plugs. Is there any style that you find better than the rest (ie: V-grove, platinum, iridium etc.). I have definitely been eyeballing the mpguino and I will probably build one in the near future.

P.S. Anyone want to buy a barely used set of 4 Bosch platinum +4 plugs lol.

[Vince-HX]

I'm running iridium Ngk's, they work great for me and i'm posting up some great numbers with them. Currently @ 200 miles and 3/4 tank

How long has it been since your cap/rotor/plug wires have been replaced?

Valves been adjusted recently?

And just so you know, its not that hard to switch to a manual 5 speed

[nasoj007]

It's only been about a month +/- since I changed the plugs,cap and rotor. I didn't change the wires as the cheapest set I found were like $160... for 4 wires!!! What?

I have no idea when the valves were last adjusted but I'm sure their due( and a new timing belt to boot).

Unfortunately a 5 spd is out of the question as my girl can't drive a stick. She might get her own car yet lol.