Thursday, June 12, 2008

Hypermiling - this is something new?

I've just started catching on to the fact that a new trend is emerging due to the ever-increasing cost of gasoline. Now we're at $4 a gallon and I can't imagine how it will come down any time soon if ever.

So there's this story on ABC News about "hypermilers" - people who, by altering their driving behaviors, are improving the MPG of their cars to above the original EPA ratings for the cars.

I had actually first noticed this some months ago on a forum called Clean MPG. Members there discuss their approaches to improving mileage, and tout their results.

There is a lot of good info in these sources. But what surprised me most was that I had discovered most of these techniques, and even some that they don't mention, independently over the years.

I think it started when I got a used 1996 BMW 328i. One of the features I found most interesting was the "MPG" gauge on the dash board, right under the speedometer. It was easy to see how driving habits would affect this gauge - being stopped would register zero MPH and acceleration would yield low numbers. But cruising along at a constant speed, especially if it was a moderate speed, would yield something like 40MPH, which is pretty good for a 2.8L six-cylinder car putting out 190BPH.

Then, the second feature of that car that I began to learn about was the trip computer. This system would calculate the average speed, MPH, the amount of miles left on the current tank of gas. With these tools, I started to learn how to drive more efficiently. And if anything were wrong with the car, i.e. low tire pressure, bad gas, engine not running right, etc. I could immediately see a reduction in mileage.

Here are the main things I learned to do to get more MPG (some are already mentioned above, some are not):

1. Slow down. Driving too fast, i.e. more than the optimum speed to get the best MPG will definitely eat gas. On the highway, there is not much difference in MPG between 45 and 65 for most cars. But faster than that and wind resistance, and having the engine at higher RPMs begins to cut into efficiency.
2. Accelerate slowly. Gunning the car from a stop - remember physics here - is applying the max energy to get the car moving when it doesn't want to (inertia). Slow careful acceleration is better, although it should be practiced within reason especially if there are cars behind you.
3. Try not to stop, if possible. Stopping and starting rob the most MPG from your car than anything else. Starting (see above) takes a lot of energy, and stopping just turns forward momentum into heat (brakes).
4. Make sure you have good, clean oil in your engine, and the right amount of air pressure in your tires. In fact, you may want to inflate the tires closer to their cold max than you normally would. This decreases rolling resistance.
5. Coast down hills in neutral, especially if you can maintain an appropriate speed for that road. I don't advocate turning off your engine because you will lose power steering, and reduce lubrication to drive train components in some cases.
6. Fill up in the morning, so that your car and the gas is at a lower temperature (slightly more dense). Fill up on the first (slow) notch on the pump.
7. Time the stoplights on your route to figure out if there are relationships between lights - this can often help you arrive at intersections when the lights are green, rather than having to stop every time. I've noticed that here in Albuquerque, every once in a while, the light timings change. Not sure why, but I suspect that city engineers are experimenting with traffic flow based on light timings.
8. Choose routes that have the least stops. This may actually take you farther, but the reduction in consumption by not having to stop and start as many times may outweigh the increased distance. Plus, you won't be wearing out your brakes as quickly, either.
9. Choose routes that have as few left turns as possible. There is a lot less waiting to turn right than waiting to turn left.
10. Always hug the inside of the curve, or take the inner lane around a curve. This means that you actually go less distance since the smaller radius means smaller circumference. Although this does not show as increased MPG, it adds up slightly over time to less actual distance traveled. As with slow acceleration, be careful not to weave in and out of lanes with other cars around.

With these techniques, I've been able to consistently get 30MPG out of a car that is rated 22 city, 29 highway, has 6 cylinders with 225BPH, weighs 3800 lbs, and is a full size, four door sedan. On the round trip to Taos a few weekends ago, I got 34.5 MPG out of a tank of gas. Sure, 40, 50 or more MPG would be better. I bet you can get those kinds of figures out of smaller, 4 cylinder cars with EPA est. 25 city, 35 Hwy ratings. Give it a try!

3 Comments:

OpenID klanggestaltung said...

Hypermiling is very common over here in Germany (where fuel is around 7$ a gallon)

We can improve "mileage" greatly by changing the overall driving habits like "do I have to drive all that miles I usually drive or can I cut down?" or "can I give a friend a lift" or "can I get a lift from a friend". That's fun because of cost reduction and enhanced social life...

3:04 PM  
Blogger Karl said...

I totally agree! And I work towards the same kinds of goals. It's not easy sometimes here in New Mexico because everything is so spread out. But we make an effort to consolidate trips and carpool when we can. Every little bit helps!

Thanks for your comment.

6:53 AM  
OpenID klanggestaltung said...

The point is: we use a finite resource here. So even when it's cheap at the moment (and I believe it is cheap compared to the next decade's prices) it's wise to reduce usage where we can. Same goes for electricity (my office PCs would use EUR 80,- when I would just switch them off, I need to cut power to safe here) and heating / cooling of homes.

9:54 AM  

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