Yesterday Mapgirl turned me on to a Washington Post article about a practice called Hypermiling. It's basically driving a hybrid (or any other car) in a manner that maximizes mileage. As anyone who has read the page about my civic knows, I'm proud of the miles per gallon that my driving habits provide. So here's my handful of hypermiling tips for drivers, some of which are repeats:

1. Drive a stick shift. I truly believe if you're not driving a manual transmission, your car is driving you. Most of the time an automatic transmission will make the right choices, but it can't see everything you can. A torque converter, the device that transmits energy from the engine to the wheels in an automatic transmission, has an 10 to 20% efficiency loss under 40 miles per hour on most cars.

2. Shift slow and low. I shift from 3000 rpm to 2000 rpm on every gear, with a little variance for actual road conditions. I rarely go above 4000 except to get out of trouble on the road or on a very short exit ramp. Shifting at higher RPMs gives you more power and feels sexier, but shifting lower gives you more mileage. If you must drive an automatic, the car will do this for you if you accelerate slowly.

3. Use cruise control. If you have a manual transmission, the car will not be able to downshift you to slow down as you go down a hill. It will simply keep you at speed to ascend and then let off the gas as you go back down, which is exactly what you should be doing. All the other times it will keep your engine at exactly the same speed (although your throttle may vary to maintain it against gravity). Some days I will have my car in cruise control for all but a few minutes of an hour or better on the road. In an automatic, your car will slow you down on purpose, so you want to disable your cruise control in hilly areas and do it yourself. It will also keep you from "creeping" up in speed without realizing it. In a perfect world you could also set the "throttle control", as a constant throttle position is better than constant engine speed for efficiency.

4. Drive the speed limit. My car is a pretty nice place to be. I've got like 150 satellite radio channels, climate control, comfortable seats, and a phone. The only thing that getting to my destination faster is going to give me is a chance to start working or doing chores earlier. A ten mile an hour speed difference on the highway will "save" me maybe fifteen minutes a day.
   
   This is easy to do on I-83 in the city or I-695 but even I wouldn't pretend that it's possible on I-495 around D.C. or on the more aggressive parts of I-83 near the PA line where drivers are consistently go 10-15 miles above the limit. Good mileage is important, but part of defensive driving is knowing when to keep the speed differential between you and the other guy within reason.

5. Stop using the brake to slow down. Wind resistance and friction already do a pretty good job without your help. When I used to commute from Hunt Valley to Parkville, I had a game with myself where I couldn't touch the brake more than five times in my 17 mile trip. I always scanned 7 to 10 seconds ahead, conditions permitting, and let off the gas a lot sooner at the sight of brake lights than I would have otherwise. A lot of the times, timed down-shifting and coasting had me in 2nd or 3rd gear just in time to apply a little gas as the other car's brake lights went off and traffic started moving again. I also "lost" a lot when everyone around me was driving like an idiot. Sometimes you just need to stop quickly through no fault of your own.

6. Empty the car of junk. Every extra pound in the trunk costs you money to haul around town for no good reason. Keep the spare tire and jack.

7. Change your oil every 3000 miles. Engine friction wastes gas and decreases engine life. I'm no mechanical expert, tho. I just do what I'm told as close to the schedule as I can.

8. Check your tire pressure. Proper tire pressure makes your tires more responsive in dangerous situations, and doesn't waste energy on friction from excess contact. Don't overfill, as the possibility of a blowout is even more dangerous.

9. Coast. Its all about paying attention to the road and letting your momentum do all the work. In fifth gear at 65mph without pressing on the gas pedal I get around 81 mpg. In neutral at 65 mph my Honda Civic gets 325 mpg. It's actually illegal in Maryland to drive with an open clutch (manual) or in neutral (automatic), but it's also illegal to speed and drive carelessly, neither of which I'm doing when I'm hypermiling. It's also a dumb law and almost impossible to prove unless you have an accident and your car's black box tattles on you. Coasting is about the only thing on this list that could get you in trouble so make your own decision on whether you are nimble enough to stay out of it.
   
   Some examples from around Baltimore: On I-83 between the county line and Cold Spring Lane, it's possible to coast at 55 to 60 mph in neutral all the way for almost a mile and a half. On I-695 eastbound at the big drop-off before Dulaney Valley Road it's possible to go about 3/4 of a mile open clutch without a drop in speed. Leaving the clutch open between shifting on St. Paul Street south of North Ave. will often left you shift out of 1st and into 3rd about 15 or 20 seconds later, lights and traffic permitting. These are just a couple of local examples. Some places like Northern Parkway coming down to Falls Road are so steep and crowded even I just leave the car in gear for best control of my speed.

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