New guy with a Honda
 

Hi there. I drive a 2011 Honda Civic LX, five speed stick. It's a good car that usually returns 31 to 32 mpg in my mixed driving, but I've got the tinkering bug. For the moment I've installed a set of the more aerodynamic wheels from the Civic Hybrid, wrapped in some LRR tires. I'm interested in improving my aero to reduce drag, without putting my warranty into jeopardy.

From what I understand the Civic Hybrid has underbody panels that should work on my sedan. Is it a simple installation, or will there be drilling involved?

And what about the Civic Hybrid's little rear spoiler? Is it just for looks or does it actually do something?

Filled up this morning, more out of curiosity than necessity. 33.5 miles per gallon, a decent improvement over my last tank at 31 miles per gallon.

Welcome to ecomodder.

33.5 mpg is OK, but surely there's a bit of room for improvement ;)
EPA numbers being what they are, you should be able to beat the highway spec in all around driving with mild hypermiling techniques.

Driving slower helps - driving faster only burns more fuel.
I've shaved 12 mph from my usual highway speed, yet over my regular 30-mile commute, it hardly changed the time or the average speed for the trip.
The catch is that once on the highway, I no longer slow down from my reduced normal speed, unless I absolutely have to ;)
Day-to-day traffic variations have more effect than the 12mph reduced cruise speed.


Have you already increased the tyre pressure ?
You can safely go up to the sidewall max. pressure, even if Honda recommends lower pressures (for comfort).
The ride will get harder, but it should not get bouncy.


If it's just a small deck-lid spoiler, nothing obtrusive, shaped like the spoiler on the 2012 HF or hybrid, it'll be OK.


If the underside panels fit, they'd help as they do on the hybrid, but may not be cost-efficient depending on their price.
Plenty of people have made their own belly pan using coroplast (which is like plastic cardboard) from left-over election signs etc.

The tires are currently set at 35 PSI. When I get home this evening I'll bring them up to 40 and see how it goes. They're rated for 44, so that'll give me a little leeway for peace of mind.

The driver needs work. I remember doing some tests a long time ago on the highway, looking at the difference in going the posted limit and going 5-9 MPH over. As I recall it made a noticeable difference in my efficiency, and it wouldn't be the most difficult thing in the world to change.

The 2011 Civic Hybrid's rear spoiler (which is what I would use on my own car) is a small lip on the edge of the trunk. Not a huge wing or anything like that. My mentality as far as modifications go is that whatever's on the Civic Hybrid is probably going to be beneficial on my LX. The front air dam is the same on both cars, and it curves around quite a bit to shield the front wheels from airflow. Airdam/deflector in one piece, as it were. I ordered up some rear tire leading edge deflectors that are on the Hybrid that aren't on my car, so we'll see how those go. There are also some trailing edge pieces I could add. Maybe next paycheck.

The big purchase I'm working towards will be completing the car's underbody panels. I'm intending to focus on improving aerodynamics over the next few months and working on my driving skills.

Grill block. Its cheap, easy, and gives good results.

Other than that, seriously look at driving technique. It is completely possible to double your mileage with driving technique alone (albeit a lot of work). Simply being an aware driver following the speed limit and anticipating lights can get you a pretty easy 30% over epa ratings. You'd have to mod the heck out of your car to get a 30% gain.

I've been working on a new route to and from work. It's a bit longer in distance and time, but it consists of long periods of uninterrupted cruising at 50 MPH. There's still a good bit of stop and go don't get me wrong, but I've cut out probably 50% of my bumper to bumper.

Grill block - is this an all the time thing? Anything I can do that won't damage the car (mechanically or, to a certain extent, visually) I'd be interested in trying.

Your 2011 Civic still has a grill that could take temporary blocking with black foam plumbing pipe insulation well. It would not mark paint, be cheap, easy, and painlessly reversible. You might even like the look, which will be fairly stealthy anyway.

Second tank is a bit of a bummer! 33.056 MPG. That's with the new route that features far fewer traffic lights and more sections of uninterrupted cruising, tires at 40 PSI, and driving sedately.

Don't be discouraged. There are many many factors, including temperatures, time of day, crosswinds, minor changes in driving style that none of us would detect but that instrumentation could show were deleterious.

And don't forget the possibility of pump error. It can swing your calculations significantly. Always do your fills with the tank closer to empty, always fill at the same pump, always choose the slowest automatic fill speed, always stop filling at the first click.

Third tank was 31.9 MPG. Maybe it's the cold snap, but it sure hurts my efficiency ego. My car originally came with a front license plate bracket that I removed because A: I think it looked ugly, and B: it isn't required in Georgia. For the grill block, I was thinking of making something out of black plastic roughly the size of a license plate or slightly larger and mounting that to the grill via the bolt holes used to hold the front license plate bracket on. It would be somewhat recessed within the front bumper. Would this have a desirable impact on drag by partially blocking air entering the engine bay, or would this create more drag?

Grill blocks are generally acknowledged to help. It can reduce warm-up times and drag. Generally the more flush with the bumper, the more people think it helps aerodynamics. The reason is that the goal it to get air moving around the car as efficiently as possible. Use the forum search function for foam pipe insulation grill block. You'll find good temporary possibilities. BTW, there is no good reason to continue running the tires under-inflated. The ride is more comfortable at 40psi, but you are trading FE for it. There is no safety difference. You would benefit from going to the full sidewall pressure (at least).

Do you have an aftermarket gauge, like and UltraGauge or a ScanGauge?

I am operating ScanGauge-free at the moment. I might have to put one on the list for tax return expenditures, if Uncle Sam is kind enough to give me some of my money back. Last tank was 30.1 MPG. It seems like the harder I try to drive efficiently and the higher I jack up my tire pressure the worse my numbers at the pump get. I'm sure a ScanGauge would help me target where I'm going wrong in my efficiency attempts.

I've got just a few more Civic Hybrid aero bits to add. Last night I mounted the rear fender liner trailing edge deflectors. It seems like they're designed to direct air from the rear wheels toward the diffuser. Should be interesting. I have a pair of leading edge deflectors to add, followed by completing the underbody paneling. I still can't decide about the Civic Hybrid trunk lid spoiler though. It's a hefty chunk of change and the best information I've received so far from my archive crawling has been that Honda put it on the Hybrid for a reason, probably an aerodynamic reason, but I'm hesitant to spend $250+ on the spoiler and drill holes in my trunk lid because the general hunch is it would have a positive impact on aerodynamics.

about the deck lid spoiler. I got myself a replica one that was unpainted for 80$ and just put vinyl on it and used 3M double sided tape so no drilling required. cheaper than buying the OEM.

i also installed the under body panels and believe they do help. you do need to drill holes for 2 of them but i didn't and they are holding just fine

heres a link to my car and what i have done for some ideas. its not much but something

http://ecomodder.com/forum/showthrea...ing-17911.html

could you post a picture of the rear fender liners?

Your hesitation is smart. Maybe it makes some difference, but it would take a very long time to recoup $250 from it. If you have good fabrication skills and you order the stock paint color, you might make a replica for less.

Grill block alone made a 5MPG jump in my mixed MPG on my 1994 Civic LX.

https://fbcdn-sphotos-a.akamaihd.net...39496492_n.jpg

I screwed thin lexi-glas panels straight into the bumper using really small screws. Since it's a brand new car, I'd go a less invasive route. Post a good pic of your front grill and I'll see what I can do for you.

Photographing the fender liners is.... difficult. Search Google Images for 74551-SNA-A00 or 74591-SNA-A00 to get an idea. Installation is amazingly easy - just drill two holes in the fender area (there are dimples to show you where), insert screws, and pop in a clip. Took me five minutes in the dark holding a flashlight.

My car is black, so seeing the grill is quite difficult. I browsed for a photo of a lighter color sedan and found this.

http://image.motortrend.com/f/323340...e-quarters.jpg

It may be difficult to see but the honeycomb-textured plastic on either side of the main grill is solid save for maybe 1/5th closest to the center grill. In other words, no air is getting through. The upper grill (the portion with the shiny plastic and the H badge) does allow air through.

I'd say you're still getting some wind resistance at the honeycomb. It'd be nice to have the air pass over it without entering in the first place. If it weren't so new, I'd enclose the whole lower dam and honeycomb areas completely, and get an accurate temp. gauge or ScanGauge just in case the upper alone doesn't provide enough airflow.

Well, Uncle Sam wants more of my money this year, so ScanGauge isn't happening any time soon. Filled up today, 30.1 MPG. On the plus side of things, I installed the leading edge air deflectors for the rear wheels. The only aerodynamic pieces left to install will be the two pieces of the belly pan. After I get through paying Uncle Sam I think those'll be my next purchases - maybe a month out?

Drove 98 miles and decided to fill up and see if my driving has improved at all. 32.2 MPG was the result. Better, but still nowhere near where I want it to be. This is proving to be slightly frustrating.

Take heart, because you might have done better than your calculations show. We just can't know. Ninety-eight miles distance and about three gallons is not enough to give you a good chance at an accurate calculation with the crude equipment we have to work with. Pump variations as to when they click off can completely throw off your calculations. Easiest recommendation is that you wait until as close to empty as is safe and practical and then refill, that you refill at the slowest fill rate setting, always use the same pump, and stop fueling at the first click (don't "top-off").

You pumped up the tires? You are driving slower? Speeds like 60/65mph on the freeway? Not warming up the car before driving and other things? If so you'll see benefits as long as you are not racing around the city streets.

Good luck... getting it right takes some time... you have to enjoy the process in order to stick it out. And don't let mod-frustration cloud your enjoyment of a lovely new car. It's a privilege. So dig it. :)

[EDIT: START A FUEL LOG HERE AT EM! Enter gas prices as well as your other fill data and the EM fuel log will show you an estimate of savings. Psychologically, seeing the slowly mounting savings estimated will help you find the cash for that ScanGauge! Eventually!!]

Per your advice I started a fuel log, and it's been interesting to track my progress. My car seems to hover around 32 MPG with my usual commute cycle, although I was able to hit 36 MPG on a highway-heavy tank at one point. Right now my financial priority is to pay the car off, but once that's done I'm going to finish with the Hybrid aerodynamic upgrade by installing all the belly pan components. I had a look at a Civic Hybrid on the road yesterday - I couldn't tell for sure, but it looks like the Hybrid's grill comes from Honda largely blocked out. I'll have to see if I can find one sitting still that I can examine, but it certainly looks like another interesting part to add, assuming the R18A1 motor can get sufficient cooling with a blocked grill.

Congrats on 36mpg! Every bit counts. And you're 17 bucks richer! ;)

Until you get a gauge, here are a couple other ideas you can do without a gauge. You could easily turn off your car and coast your manual transmission up to red lights and down hills. Engine off coasting reduces city driving losses from stop/start. And at other times you could also use the car's deceleration fuel cut off function: slowing to lights or going downhill, shift into a gear that will put RPMs up to 1700 or 2000 and the computer cuts fuel to the injectors while you decelerate. I do it all the time on my 1998 civic now. My O2 sensor readings show zero voltage within a couple seconds, meaning no fuel or almost no fuel is being burned even though the engine is still "on." Saves brakes slightly too, I guess.

Good luck!

welcome

Are you using Pulse and Glide (Engine-ON coasting)? I'm also in a 8th Gen 5MT Civic and I couldn't break 36 mpg and was getting frustrated. Started using P&G every chance I get and I've gotten as High as 44 mpg!

Also California98Civic how do you restart when you engine off coast?

The technique is known as "bump starting." Here is a good discussion of "how to": http://ecomodder.com/forum/showthrea...html#post10951