I just averaged 50mpg on a quarter tank of gas with my '95 Civic EX
sedan. That's the highest I've ever gotten, and it's not representative
because of the small sample and because that driving was 90% highway,
but I still find it impressive. What other high numbers are you folks
getting? BTW, I practice 'Super-Miling' which is just modest, safe steps
to increase economy, unlike 'Hyper-Miling,' which can be dangerous. I
run the tires at 38psi cold, coast with the engine *on* when possible,
and accelerate gently. I also try to 'time' lights so I don't have to
stop more than necessary. I generally get about 41mpg in Summer, a few
less in Winter. I use midgrade gas because the gearing is so high I need
full engine power to get the best economy.
I regularly get 40mpg on the highway with my 2004 Civic LX automatic. I
usually drive about 10mph over the speed limit, and my driving style is
moderate but not heavy or light. I have my tire pressures about 2psi over
what Honda recommends, and I use regular unleaded fuel (87 octane).
Speaking of tires, I just replaced the horrible Bridgestone Insignia's with
a set of Falken Ziex ZE912's, so I'll have to see how much the step up in
performance will affect my mileage, if at all.
It's a shame that hypermiling gets such bad press. I'm doing much the
same as you, and get high 30s (city and highway) in an old Accord wagon.
Having a manual transmission helps; you can coast in neutral and
accelerate with the engine in it's most efficient RPM/Throttle envelope
without the transmission downshifting. Back last summer, when gas was
4$, I had a fair number of people ask about my mileage. When I told
them, there was often a mild backlash accompanied by the accusation,
"Oh, you're one of those hypermilers." I then had to explain that I was
a 'good' hypermiler. :) I watch my mirrors, try never to hold up
traffic, don't run red lights, etc. I may not get 60MPG, but I'm not
tearing up my car or becoming a traffic hazard.
I'd argue that anyone exceeding EPA is a 'hypermiler,' but agree that
some of the hardcore techniques do little except alienate the average
driver. We've all seen the news segments - "See how Wayne gets 65MPG!"
Most people are curious, but react with a giant 'WTF?' when they see
one of the HM 'stars' putting down the road trailing a queue of pissed
off commuters, turning the ignition off while moving, taking freeway
exits at clearly unsafe speeds, pushing the frigging car across parking
lots, bragging 'my tires have 70psi,' and engaging in other hare-brained
behavior. If HM proponents could keep their ego in check and act in a
less OCD fashion they might manage to get somewhere in terms of
educating the public. Simply teaching people to anticipate those #$%^
traffic lights will instantly increase Joe Sixpack's city mileage by
Running your tires at 38 psi may be bad for them and dangerous for
you. When you heat those puppies up to 200 F or so (get a pyrometer)
you'll probably be around 45. Which is probably near the realistic
limits. Also, you are changing the shape of the tire and the wear.
And, unless you've changed your struts up, your handling is worse. And
don't get me started on wet weather driving.
- dillon I am not invalid
The RMS Titanic sank on April 15th. US income taxes
FWLIW, 38PSI cold is about right for my 92 Accord. The factory
specifies 32PSI, but that gave me a _lot_ of excess edge wear. Hot
pressures are, as you guessed, mid 40s. This is great on the freeway,
but firm enough make you watch for potholes and whatnot. Any dirt road
travel strongly 'encourages' you to soften things up!
Wet weather performance (resistance to hydroplaning) actually improves
with increased pressure.
The tires are stamped with their maximum cold pressures, and the
manufacturers give those specs knowing exactly what will happen when the
tire heats up.
If the tire is specified to take 38psi or more, then there's no danger.
It may go up to 45 or even 50psi when run on the freeway on a hot day;
the tire manufacturer has taken all of that into account for you.
My Prius specifies 36psi, for God's sake.
Exactly the same feeling I am getting.
And for what reason person can torture themselves?
It is for the global warming and to save Mother Earth? :-)
It is probably to save 5-6 dollars when refueling the tank
and spend it later on a prematurely blown tires or repair
and medical bills after a crash on slippery road after rain...
BTW - is there any reason at all for running Civic on mid grade gas?
This engine was designed to run on regular, so there is no knoking
which can be avoided using higher octane gasoline...
On 4/24/09 9:02 AM, in article firstname.lastname@example.org, "Pszemol"
They all have knock sensors that will make any knocking immediately
disappear, probably before you even notice that its doing it, regardless of
what gas you use vs. what was actually spec'd for the car.
There was some traffic from Honda several years ago that indicated some of
the cars were actually designed for premium fuel and would give better
mileage and performance if it is used, but rated for regular and depended on
the knock sensor to make it all work.
The way to find out if yours is one of those is to run several tanks of
higher octane fuel in it. If the mileage is consistently better then you
can benefit from it. If it isn't, stick with regular. AFAIK, all the
Civics are designed for regular.
Believe me, I started using midgrade reluctantly. This car has
freakishly high gearing, and I first started using it so I'd be less
likely to stall it starting out in first on hills. (And no, I'm no
newbie to standard transmissions. Between the tall gearing and the idle
being set at 600, the car really is touchy.) It worked, and I also
noticed a 10% increase in economy. Since midgrade gas was/is only about
5% more expensive, it made sense to keep using it. The thing about knock
sensors is they only stop knocking - they don't increase performance. In
fact, they are there so the engine can run a more advanced timing curve
when you use higher octane gas. This Civic is the only car I've had that
got better MPG on midgrade.
Your car has identical low gearing and final drive to all other Civics
prior to it. But your 4th and 5th are in fact higher than they used to
be, probably to help improve Honda's CAFE numbers.
(I do very much wish _my_ 4th and 5th were higher than they are...)
If you DON'T have the D15Z1 engine, no-load idle of 600rpm is too low.
Pump octanes have zero effect on whether an engine is more or less
easily stalled at lights. If there is any effect at all, it's a
perceived one, not an actual one.
Boosting the octane rating of gasoline serves only one purpose: to
prevent the tendency of a fuel/air mix to self-combust all at once in
the absence of a controlled flame front. Self-combustion is what's known
as "knocking". On its own, higher octanes have no other meaningful
effect on engine performance.
Engine control systems are only capable of increasing performance with
higher octanes if they are designed to do so. Your Civic's is not. The
Civic is designed for 87 pump octane. Its engine management is not
capable of advancing timing past designed-in limits that do not take
higher octanes into account, but can only /retard/ timing if knocking is
Your knock sensor is intended to decrease the tendency to knock, not
/specifically/ to prevent engine damage, but to decrease emissions of
nitric oxide (NO) while still maintaining the best power and mileage
that can be achieved without engine damage.
I've conducted my own fairly extensive tests of different octanes. Given
that testing of any meaningful length of time necessarily involves
seasonal temperature changes, my results were inconclusive. If anything,
I got a very slight /reduction/ in mileage with 91 pump octane versus
Interesting. A few points: I had a problem with stalling when
starting off going up inclines, not at lights. That has improved,
possibly just from the midgrade cleaning the injectors. As for the
increase in fuel economy, that's real. And there is a white line across
my tach right at about 600 RPM; it's obviously there to tell owners that
the low idle is intentional. What's the D15Z1 engine? I suspect I may
have it. Finally, I wouldn't mind having two overdrives (4th and 5th)
but *third* is also way too tall. Trying to accelerate up a hill in
third, even after revving the bejesus out of it in second, is
discouraging. My 91Hp series one Si would kick this car''s 126hp ass on
the dragstrip. Still, as long as it keeps getting 40+mpg in Summer, I'll
live with it.
No, that's not why they're there.
Knock sensors are there so that when you use a gasoline that does NOT
have the anti-knock properties that are called for in the
gasoline--let's say you used a lower octane gas--then the engine doesn't
But when the engine is already designed for 87 octane fuel, and if
you're using a proper 87 octane fuel (not piss water), then the knock
sensors don't come into play at all. (I am ignoring the effects of age
and bad maintenance causing carbon buildup inside the combustion
chamber, which would lead to knocking with 87 octane fuel, which means
that a higher octane fuel will help. Rather, I am discussing a properly
maintained and clean engine.)
Again, the knock sensors don't come into play at all. You can put all
the higher octane gas you want in, and the knock sensors don't move the
timing around to keep the engine just at the point of knock. No, the
knock sensing system is designed to work with fuels lower than what the
engine was designed for. The system was NOT designed to advance timing
in the presence of higher octane fuels that are beyond the octane rating
specified by the engineers.
well, the truth is between the two of you. knock sensors allow the
motor to run the most advanced curve it can without knock, regardless of
fuel. at the edge of the envelope, knock can vary tank to tank, rainy
days, vs. non-rainy days, cold, hot, etc. if you can figure out where
the knock point is, you can move timing accordingly. if you don't know,
you just have to set it back, and leave a safety margin. that means
very slightly less power and/or fuel economy. in this day and age of
powerful engine computers, there's no reason not to pursue that marginal
There is a contradiction being promoted here: that my car is
designed for 87 octane gas only, and that it has knock sensors in case I
use gas below 87 octane - below Regular grade. Perhaps Honda doesn't
respect American gasoline? BTW, my Civic Si also did better power-wise
on midgrade (but with worse fuel economy), and IIRC it noted that higher
octane gas was preferred in the manual.
Not quite. It is possible to have gas that's nominally 87, but is
contaminated, of substandard quality or has degraded with age.
In any case, the primary purpose of the knock sensor is EMISSIONS, not
engine damage. Protection against engine damage does allow the computer to
advance the timing as far as it can without risking detonation, but it can
only go up to its designed-in limits, which are configured for 87 octane.
not necessarily true. the more advanced, the more NOx because
combustion temp is higher. but the trade is better fuel economy and/or
power. thus, in an ideal world, you want the ignition as advanced as
possible for any given day, and the only way to determine the max limit
is to use knock detection.
modern ignition timing algorithms, for want of a better word, are highly
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