Substantial hypermiling observations (guest author)

I’ve commented a few times about hypermiling - driving an ICE do maximize MPG.  I think that many of the techniques are dangerous and do not recommend it.  However, in some cases, the claimed results are impressive.   The only way to separate fact from fiction (besides gambling $10M in VC $) is do actually try it.  At my request, my friend and co-worker, Greg A, wrote up his experiences with and insights about hypermiling.

After trading in my ’99 Toyota Sienna and buying an ’08 Honda Civic (non-hybrid), I was in a mileage giddiness that led me to consider hypermiling.  I had heard a couple of co-workers talk about it, read an article, and listened to a radio interview of an “expert”.  With all this information, I decided to try it.  My Civic gets about 29.5 MPG with my “normal” driving habits.  I’m probably a little aggressive, speed some, and accelerate too quickly.

Note:  MPG readings were from miles and poured in gas.  NOT the Trip MPG that the car uses.  Those things LIE really bad.

The summary is that, for me, it isn’t worth it.   I don’t think hypermiling is bunk, but I also don’t think it is a safe way to save gas mileage unless most of the other people on the road are using it.  Read more specifics below:

(source: Ecomodder - hypermiling tips)

The things I attempted to for the tank of gas were:

1. Accelerate slowly – They mean really slowly.  Even to the point of using your cruise control to limit your acceleration rate.  I didn’t use cruise control, but I did this in the context of item 2.
2. Keep engine RPMs low – This is really a way to measure one.  This one was from the radio “expert”.  Most of the sites don’t talk in these terms.  The net effect is slow acceleration.
3. Drive the speed limit – The civic seems to do 2000 RPMs at 66 MPH on flat ground.  This works for most roads and toll-roads around here, but doesn’t really help in rush-hour traffic.  I did this to see.
4. Turn off engine at red lights – This is also a myth and dangerous.  I did this at one light near my office where I usually end up waiting 3 minutes.
5. Turn off engine and coast – This is really dangerous.  Obviously, saves gas, but ugh. No brakes.   No power steering.  Just not worth it.  I actually tried it a couple of times.  One was near my home on a minor hill at let me take a corner and my drive-way without the engine.  The other was a large hill near my workplace in the middle of the night.  I went about 1.5 miles without my engine on, but was going about 20 MPH when I started again because traffic was passing me. 
6. Turn off A/C – Hey, I live in Texas.  Not likely.
7. Turn sharply at speed – When possible, but not commonly done on my normal commute.
8. Time lights and congestion to avoid stopping – I tried this, but this is a learned skill.  It takes time and knowing your commute.
9. Engine braking – This is an explicit method of achieving item 8.  It is often illegal in many places. 

I did have one rule: If I was annoying other drivers, I would not continue the technique.  The slow acceleration meant that I would be slower than most traffic goers, but wouldn’t get me honked at or continuously passed.

I didn’t try pulsing (going 10-15 mph over and coasting to 20 mph and repeat).  This seemed to really break rule 1.

The result was about a 5% savings, 31 MPG.  Nothing to laugh at, but I expected more.  After all, I had read about some remarkable success.  After the attempt, I researched some more (Wikipedia) and more (Wisebread) and others.   Some interesting things I found out.

• How old and type of your car matters.  Automatics are easier to play some of these games as well as older cars have better non-powered equipment.  More recent cars can actually be damaged by running with the engine off.
• New cars are really smart.  Go figure the car industry needs to save MPG somehow.  My car knows when it is coasting and doesn’t have to inject fuel into the engine.  In fact, putting the car in neutral wastes more gas than coasting (the fuel injector has to put gas in to keep the engine turning).
• You have to really work to do hypermiling safely.  Primarily by timing lights and congestion.  The hard part is getting used to take your foot off the gas to slow do approaching a light (and upsetting many people around you who expect you to race up to the light and stop).

This entry was posted on August 2, 2008 at 1:54 pm and is filed under Hypermiling, ICE Cars. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response or trackback from your own site.