wheel_of_steel

Do you do it?



I've seen some pretty crazy stuff that has been talked about on some hypermiling forums, such as taping up panel gaps and planning your trip according to the wind etc... but there are obviously more achievable/less annoying ways to up those em pee gees!





I noticed in another thread that most members here take their fuel economy all the time, so what tips and tricks do you use to increase your fuel economy?

StrikeEagle

I drive a Tiburon that gets 30mpg rather than ______ which gets not as much. The money you save by even 1-2 mpg is simply not worth the effort. Done the math, been there before. It's just not cost effective.

For example, over 100,000 miles at a 1mpg difference, you'll have saved only 100 gallons (out of about 3300 used), which is a total cost savings of only about $400 at $4/gal. For 100,000 miles. Not worth the tacky look and absurd changes needed to make the 1mpg difference.



That being said, a $2500 motorcycle that gets about 50mpg will have paid itself off in 50k miles.

187sks

Do all the time:

I air up my tires to between 35-40psi (depending on where the tires grip reasonably well).

I Keep my air filter clean.

I change my oil regularly.

I run gasoline with detergents to keep my fuel system clean.

Going down LONG hills I will push in the clutch unless engine braking is necessary and idle down the hill.



If I was trying for a gas mileage record:

I wouldn't exceed 60mph, and would stay between 50-55mph as much as possible.

Speed up going downhill, lose speed going uphill.

Shut off engine going down long hills or idling for more than a few seconds.

Occasionally I might draft a semi truck if conditions allowed.



My typical highway mileage for my Accents varies between 35mpg and 42mpg, depending on conditions and terrain mostly. I'm usually around 38mpg on highway trips. I've never managed to "hypermile" for enough distance to get a reliable gas mileage number out of it. Most highway routes with 400ish miles of ground to cover without being slowed due to cities it would be unacceptably slow to go 55mph the entire way.

Stocker

Airing up the tires has the biggest effect on my car as far as I can tell.



If you want to spend money to increase fuel economy, use this calculator first.

wheel_of_steel

Interesting feedback from all. I especially like that excel chart, stocker. From some 'back of a business card' math, the work I propose to do will take about five months to pay off... I find this stuff pretty interesting anyway, I'm going to try out a couple of measures to begin with:



Burn and Coast Driving



Basically, accelerate up to 60, then switch to neutral, kill the engine and coast down to 50. Rinse and repeat. The idea is that the engine has much lower brake specific fuel consumption during mild acceleration than it does during low load/mid rpm cruise. Apparently you can net an easy 10% gain in fuel economy, even if you just let the engine idle during the coast period.



Driving With Load



It is simple, just don't exceed a certain level of manifold pressure as you drive along. It is usually monitored with a vacuum gauge, but you can do almost as well by just keeping your foot in the same position as you go up and down hills.



Other than that, I'll up my tire pressures from 34 to perhaps 38 psi, remove my useless roof racks, and perhaps install a jaycar 02 monitor.







That way I can optimise the burn period during Burn and Coast driving by opening the throttle as far as possible until the computer enters open loop mode.



I think the most difficult part about efficient driving is adjusting your mindset. Driving slowly just frustrates me to tears.

Whatnot

This one I have argued back and forth, and attempted to test and with my highly unconstant variables, I thins this is wrong. As when you push in the clutch, your car must idle, so that used a bit of gas. Where as when you let off the throttle, you FI shut off....but you won't coast as far due to the engine braking, and this is best done in 6th gear to minimize that affect. The best way (not exaclty the safest) is to shut your car off, that was you go into N so you are not engine braking, and you are using 0 fuel. And right before you need to get back on the gas, if you push clutch in, put in gear, let clutch out slowly, then just turn your key on (don't crank), your car is back on without using the starter. Or if you had a cable thottle, with the car off, you could just go WOT and this would minimize engine braking, but you would still have friction involved. I wish they made a switch that you could open the throttle all the way when not touching the pedal, to minimize engine braking and maximize coasting. Obvoiusly all of this is with M/T, I wouldn't try any of this with a A/T. Though most cars maintain a small amount residual hydraulic pressure for power steering and brakes, this can still be dangerous.





IMO, this is the largest thing you can do, and it was shown on mythbusters to give something like 25% increase. It is less dangerous than many think, but also more dangerous in the same way lol. First, if you have a beater, the closer you follow the safer it is, one you will have a lower speed differential and two you car brakes are generally better than his. If he hits his brakes you should be fine, but if not, you might bump him at 5mph relative speed before you can hit the brakes. Then there is a danger zone, where if you don't react fast enough you will nail him at 20+mph, and then back to a safe distance, which just gives you more reation time. But the danger isn't really in braking is many think, rather in being blind ahead of you. If a 18 wheeler sees a big piece of wood or something in the middle of the road, he might know he clears it over his center.....and unsuspecting you will be screwed when it reaches you. Or, I saw a video of a big truck fling a 2-4 thorugh a guys windshield from his back tires, no time to respond at all.






I don't really do it too much thinking about things like the video, but when I did it, I saw a good 5-7mpg increase. What would be pretty pimp would be a small neodymium magnet that holds like 120 lbs and put that on your bumper and 'dock' to the 18 wheelers 'crash saftey bar' they have. I can't imagine you once you match speed you need that much holding force. Then you can N it and chill lol. Though again, obstacles might kill you, braking wouldnt' be a prob for you (though he might have ot work extra hard lol, and it is highly illegal, and stealing his gas lol. But would be neat to try once, or maybe go to a truck stop and slip a guy $20 to let you 'dock' to him.









This is the whole theory behind varable displacment cylinders, basically what I talked about in that thread https://www.hyundaiaftermarket.org/f...cement-motors/



At medium load, you have less pumping loss, BUT you are't accelerating hard, so you are still closed loop, you are higher compression, and you arn't overcomming inertia too fast. But I would recommend highly agains this if you have a diesel.

I do this often, one of my favorite reasons to have a boost gauge and AFR.



And like you said, a mindset, many live in heavy traffic and there is no such thing as not tailgating and are constantly on the brakes. IMO braking is by far the worst mpg offender. You fix your braking and your mpg's will go up a lot. Anytime you are braking, you are killing your mpgs....obviously you need to stop sometimes, but somepeople, if they just increased their following distance and let off the gas earlier you would start to coast and the person in front of you would accelerate and you could resume. But so many people use gas to get close and the second the brake light comes on, they slow way down, then have to speed back up, its killer on mpgs.

StrikeEagle

This has been busted repeatedly with today's fuel injection (vs carburation, which wouldn't have the same effect here). Whatnot went into plenty of detail, but just wanted to this. Idling takes fuel (clutch all the way in). Coasting takes none whatsoever. If you really want to get the best mileage, ride the clutch so your rpms are above 1k but below 2k rpm. This will still cause the fuel to cut off completely, but your engine won't slow you down nearly as much. Course, then you'll burn your clutch out sooner, and lose that $500 over 100,000 miles that you saved...