Hypermiling II - The Results
Since I started the experiment last month, I have increased the fuel efficiency of my car by about 33%, just by changing my driving habits. Awesome.
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Stark Raving Brad said, (89 days ago)
jesus. you've gone hog wild. i did change my driving habits and found a notable increase in milage, but nothing the extent of your efforts or results
basically, i just stopped accelerating hard at all times, and driving 80mph. i go the speed limit, do everything i can not to put my self in a situation requiring much use of the break, and coast down a lot of hills.
my mpg went from about 30 to to 36.5. and i didn't do anything very radical.
i gotta aplaud your dedication, dude.
soulcamp said, (89 days ago)
Dude, 30 to 36.5 is over a 20% increase - that's not bad. I think the acceleration and driving slower are the biggest factors, and the easiest to do. If everyone in this country just did that, we'd save so much gas, it would be unbelievable. I'm just trying to see if I can push it further, probably because I'm bored or some retarded reason like that. If I can eventually get to 35, I'll be pleased - 40 and I'll be stoked. We'll see.
chipmunk! said, (89 days ago)
how is the transmission taking to the neutral shifting? I have a 98 acc as well and the v6 version hates being shifted into gear over 1 mph. Think the 4cyl can with better clutch packs.
would could also add an intake to the engine to let it breath easier and maybe increase mpg?
Centropotamus said, (89 days ago)
Shutting off your engine while the car is in motion is generally considered reckless driving, for the reasons you've stated, among others.
Also, Pulse & Glide only makes sense if you have a shitty transmission. In a manual or late-model automatic, it shouldn't help, at least relative to maintaining the *average* speed, rather than the max speed.
Centropotamus said, (89 days ago)
I do most of my driving on the interstate, and I can go from 30 MPG to 34 MPG just by drafting behind tractor trailers.
Centropotamus said, (89 days ago)
I'm not getting a hybrid until they use electrical transmissions. Mechanical transmissions are so last century.
JasAsian v2.0 said, (89 days ago)
No more drive-through for me. Now I turn off the car and walk inside.
@Centro - how close do you have to be to actually get drafting to work?
Centropotamus said, (89 days ago)
For a tractor-trailer, not very close. That's why I draft behind them. Behind an ordinary car you have to be illegally close to get any substantial benefit.
soulcamp said, (89 days ago)
@chipmunk: My 4-cyl seems to have no problem with the neutral shift - very smooth. I've heard the 98 V6 trannies are a nightmare, and they don't recommend leaving D.
soulcamp said, (89 days ago)
@Centro: P&G seems to be very efficient at speeds lower than 50. I can pulse for 3-4 seconds at 3000 rpm, then glide for about 20-30 seconds at 1000 rpm. With my SGII, that equates to about 3-4 seconds @ 15 MPG to 20-30 @ between 60-80 MPG, on a flat surface. With a slight downward grade, and I can ride at 150+ MPG for well over a minute.
As for drafting behind a tractor-trailer, most of them here in SoCal are doing 70+ MPH. That makes a draft significantly less efficient than simply going 55.
soulcamp said, (89 days ago)
@chipmunk: There is some talk over at CleanMPG.com about air intake temp. I believe that is one of the values the SGII can display.
Centropotamus said, (89 days ago)
Automatic transmissions generally use a hydraulic moderator (functionally similar to a flywheel) at speeds below a certain threshold, generally around 35, so the real key is to make sure you're doing your in-gear cruising over 35. For acceleration, it doesn't make much of a difference, which is why it works. If you ever buy a car with an efficient transmission, it won't work. It probably won't even work in a manual.
Drafting behind a tractor trailer at 70 mph burns about as much gas as driving 55 with no one in front of you. The same is *not* true of a normal car or even a small truck.
Stark Raving Brad said, (89 days ago)
oh, i failed to mention the other act i took which improved my milage. i got new tires and an alignment. my other ones were truly on there last legs, but they also probably weren't properly inflated, which counts for plenty too.
chipmunk! said, (88 days ago)
Might also want to try a stiffer suspension, stiff engine mounts and lowering springs.
the stiffness will help in torque transfer to the wheels and not the body.
lowered springs can be stiffer in most cases and will reduce drag thanks to a lowered car.
you could also get a skid plate for the front to smoothen out the chassis (less drag)
Corey Hart said, (64 days ago)
When I first got my car I was getting around 22mpg because I was having fun playing with it.
Now I get around 32mpg. It's an automatic, so I'm not quite sure what I can do to increase that much further, besides accelerating more slowly. I use my brakes as little as possible already.
soulcamp said, (63 days ago)
@Corey: What kind of car is it?
The first (and easiest) thing is to inflate your tires to the maximum sidewall pressure, not what's inside your door. The door pressure is usually lower than what your tires can handle to create a smoother, softer ride at the expense of quicker wear and lower fuel economy. According to the EPA, you will gain 0.3-0.4 MPG for every 1 PSI. Also, the sidewall pressure is cold, so you should check after you haven't driven in several hours and adjust accordingly. The general rule is to overfill your tires (since it's more difficult to get air in than let it out) and then check and adjust when they are cold.
The next easiest to eliminate jackrabbit starts and never drive over 65. Wind resistance is huge when you get over 50 MPH, though every car has a different optimal speed (I found I get about the same MPG at 65 as 55, but the extra 10 MPH makes going up hills more efficient due to the increased momentum).
After that, it becomes more work, but the work really pays off. The key is paying attention to your momentum and trying to conserve as much of it as possible. Pulse & Glide (P&G) is probably the next big payoff, which can increase your efficiency between 20-100%, depending on how you do it. Though just simple things like letting off the gas if the light ahead of you is red can make a big difference, as well.
Check out CleanMPG.com for all the different techniques people are using.
soulcamp said, (63 days ago)
@Corey: EPA is 21/29, with a combined of 24. 32 is not too bad, but you can do better. You can probably get somewhere between 35 and 45 MPG in that, depending on how much effort you want to put into changing your driving habits.
With this last tank of gas, I added a couple more techniques. First one is Pulse & Glide (P&G). This is where you accelerate to a target speed (say 40 MPH), then shift into neutral and glide until you reach a lower speed (say 25 or 30 MPH). Then you shift back into drive and accelerate again to the target speed. This is supposed to save you lots of fuel in non-highway driving (it doesn't work well past 50 MPH because wind resistance become too great of a factor). This trick takes a lot of practice to get right, and using a ScanGauge II to see your engine load percentage is supposed to really help. I just got my SGII today and hooked it up, so I will see how that goes.
The second technique is Forced Auto Stop (FAS). I only use this when approaching a red light that I know I will be sitting at for longer than 10 or 15 seconds. To perform a FAS in a non-hybrid, you shift into neutral, then shut off the ignition for a second, then switch it back to accessory II (to reengage the electronics, such as speedometer and such). Supposedly, sitting at idle for longer than 10 seconds burns more fuel than starting your car, and there are plenty of lights around here where I have to sit for 30 seconds to a couple of minutes. When the light turns green , I turn the key, shift into drive, and off I go.
Some people combine FAS with P&G (shutting off the engine during the glide phase for maximum efficiency). However, there are several problems with this. First off, most cars lose their power steering and power brakes when you shut off the ignition. While the brakes still work, after a few pumps, they will become like truck brakes and you will have to give them everything you've got to stop. Most of the time, this is not a problem as you are coasting and most likely will not need to apply your brakes. However, it is certainly an advanced technique and requires some skill in order to perform it safely. The second, and even greater problem, is that some cars with automatic transmission will not lubricate the transmission when the engine is off. This could cause it to overheat and burnout. You have to check your vehicles owner's manual to see if and at what speeds your car can be safely flat-towed.
Overall, I am finding this process to not only be fairly easy, but kind of satisfying. A month ago, I would have been pissed to get behind someone going 55 on the freeway. However, now I find myself pissed at all the people hauling ass past me at 80. They are just wasting fuel, for no good reason, and probably every single one of them will bitch about the price of gas when they reach their destination. Also, it's kind of fun. It's like a game to see what the best score you can get is, and then try to top it next time. Driving is almost fun again.