Hi All,

I'm new to the forum and have always been interested in increasing fuel efficiency on the road. I'm currently driving a 2005 Honda Civic 4cyl 1.7L manual (5 speed) (sorry, non-hybrid - but at least I carpool to work!). Recently, after reading up on some tips to increase fuel efficiency that I read in this form, I started to be more mindful of my driving... especially being careful of quick acceleration and making a true effort to go sub-70 MPH on the highway (usually I drive about 74MPH). I also did my best to 'coast' (when appropriate and safe) down major hills/exit ramps by putting the car in neutral.

I did this for an entire tank and was excited to calculate my MPG upon filling up my tank. When I filled up, I found I was only getting 31.5 MPG when the previous few tanks I had achieved 34.5 or 35 MPG.

So the question I pose is... Do you feel that doing things like coasting in a traditional non-hybrid car increases gas mileage, or is this technique most appropriate for hybrids? I know more tempered accelerations will always save gas, so I think that did not play into my decreased mileage on this most recent tank - but am curious about your thoughts into this situation.

As a scientist, I understand that this is obviously a flawed 'experiment' as there aren't any replicates and it was very cold last week in New England where I live, but can't help to think that the coasting caused this marked decrease in MPG as this was one of the lowest MPG ratings I've received in this car. (The best was an all-highway round trip over several states in the summertime where I earned 49MPG for a full tank).

Any input into this question would be appreciated.

Thanks.

 

Hi,
I would suggest you might start by getting instrumentation for your vehicle that would give you a record or instant feedback on your performance. As you pointed out, the experimental conditions were not well controlled but instrumentation to record and sample critical vehicle parameters would help.

As for experts in driving non-hybrid cars efficiently, I would recommend CleanMPG.com that has that as their charter. Many of my techniques exploit the unique characteristics of hybrid electrics and don't translate well. For example, driving 38 mph and slower so the car can automaticly switch between electric and gas powered modes.

GOOD LUCK but I think the folks at CleanMPG.com would be an source for non-hybrid driving techniques.

Bob Wilson

 

tbarry,

You are definitely on the right track by cruising at a steady speed and going easy on acceleration. Monitoring with www.scangage.com will also be helpful.

Some people use cardboard in front of the radiator - including truckers. Short of that, turning the temperature to the coldest settings with the heater off mimimizes the draw on the coolant heat.

 

Hello, tbarry, and welcome to GreenHybrid!

I think coasting will help no matter the vehicle. For additional tips, check out CleanMPG, a site dedicated to optimal fuel economy in any type of vehicle. They have a mileage database similar to GreenHybrid's in which you'll see several Civics, even with auto trans, averaging in the upper 30s and low 40s.

 

Given the information you have provided, the only thing we can really say is that temperature may have had something to do with the drop. There is no reason why coasting in a non-hybrid car wouldn't have saved you gasoline. Ditto for the slower driving- air resistance and drag by themselves make a relatively big difference in the amount of gas it takes for the car to move forward. Without more specific data, I can't really give you much advice, sorry.

As for the 'coasting' in neutral, I don't know if this makes any difference or not, but when I'm talking about coasting, I don't shift my car at all. I just mean that I have my foot off the gas and off the brake, and I let the car coast. I keep my foot near the brake, of course, in case I need to slow down, but usually the car begins to slow slightly on its own (more quickly on a hill going up and less quickly downhill) and I move my foot back to the gas, gently.

I've done this in my mom's (non-hybrid) Prism and find that I can coast even more easily in a non-hybrid, because there's no regen. that kicks in to slow me down, and even leaving aside regen., the car doesn't seem to slow as quickly when coasting.

 

Thank you all for the replies - I've just registered on CleanMPG.com and will read their forums for more tips.

I have a followup question based on leahbeatle's response. Does anyone have any insight into whether coasting in gear vs coasting in neutral would be more efficient in a 'gasser'?

Thanks.

 

Using a scangauge I can say that coasting in neutral is more fuel efficient than coasting in gear on my Tacoma, by a significant amount. I generally idle at .2-.3 gph (gallons per hour) but while coasting in gear it can be .4-.8 gph depending on rpm. The hills I hit on my daily commute allow me to crest at 10 below the speed limit and accelerate in neutral up to 5-10mph over the speed limit, with long coasts achievable. If I keep it in gear the engine braking kills the momentum.

It possible that some vehicles now shut of the injectors in engine braking situations, but my Tacoma doesn't appear to do this. The scangauge isn't intelligent enough to tell me for sure.

 

Good choice on CleanMPG.com but as to the transmission question.

I would recommend finding a shallow, down-grade and performing your own 'rolling' test. Starting from a known starting place, measure either the ending mph or a stopping point from each run. I would recommend at least three samples in each mode so you can average the results and remove minor noise. The following shows my Amsoil vs. OEM transaxle oil testing:


Plotting the slope was a little over the top but I like to document as much as possible.

Did I mention 'walking the dogs' with a laser level and recording the paces between user measured height changes? The dogs were happy and soon learned the Alpha dog was interested in the funny 'red light'. The neighborhood was amused and the Paranoids, who live about eight houses down, came out to see what I was doing

Bob Wilson

 

Bob, you are so amusing. I hope your neighbors the Paranoids enjoyed the show!

 

tbarry

I think the scangauge will be a great help. We have one in our VW TDI and it shows exactaly what your mileage is instantly. I am going to guess your mileage is worse after coasting in netural then before because your car has a fuel cut system. If you coast in gear you use no fuel and when you coast in netural there is idle fuel consumption of .2 -.4 GPH. The scangauge on our VW will show a MPG of about 200 while coasting in netural and 9999 MPG while coasting in gear. The trick is to coast as far as possible, so start out in netural and about 200 MPG and when you know you will have to stop and you can get to the intersection at minimum speed, then put it back in gear and go the rest of the way at 9999 MPG. That should be good for 2 - 4 MPG over the whole tank....Louis