More Thoughts on Driving
In an earlier post, I talked about my plan to drive the speed limit for a long road trip from Southern California to Northern California. The experiment went pretty well, as I was able to stay near 70 for practically all of the trip. Additionally, the car I drove on the way back had a really easy to use cruise control function, which I used extensively and supposedly increased my fuel efficiency a little bit.
There is a ton of online guidance concerning all the ways one can increase the fuel efficiency of one’s car (for example here, here and here [pdf]) both mechanically and behaviorally. I’m primarily interested in the behavioral modifications that lead to increased fuel efficiency. In terms of behavioral suggestions, I think there is one central heuristic that encompasses all of them: a complete and total aversion to touching the brakes. When I drive, I’m essentially playing a mental videogame (in some cars, like the Prius, this videogame can be surprisingly literal) where I gain points for coasting and lose points for heavy acceleration and especially braking. In this way, I expect to lose as little fuel as possible to inefficient low gears and necessary stops.
Needless to say, there’s a little bit of tension between legality, safety and efficiency. Obviously safety should come first, but oftentimes legality, in the form of full and complete stops at stop signs for example, might be justifiably set aside for efficiency. If I’m going up a hill I’ll try to time things just right in order to coast to a very low speed at a stop sign and then accelerate away from it without ever having touched the brakes. Another trick is to touch one’s brakes extremely lightly so that the brake lights come on and it looks like one is stopping when really one is simply coasting then accelerating. So far I haven’t gotten a ticket, and if I do I imagine it might change my behavior. 
Despite the fact that avoiding substantial acceleration and braking is in general safer and more economical, many drivers I see on the road act like they’re in some sort of pitiful race where everyone is continually stymied by traffic laws. The maneuver that annoys me the most proceeds as follows: I see that there is a red light 200 feet ahead and immediately take my foot off of the accelerator. The person behind me, unsatisfied with my resulting speed, floors it and passes me to the left. Said person then slams on their brakes at the light while I am still coasting towards it. When the light turns green, they are at a complete stop and I’m still going 20 mph, at which point I accelerate through the light and pass them. End result: I’ve used less fuel and caused less wear and tear on my car to end up well ahead of the person that passed me.
The only difference between me and this other driver is our driving mentality. How to change one’s driving mentality from “go as fast as possible at all times” to “slower can actually be faster and save me money (and never touch the brakes!)” is not quite clear to me, but given enough reflection it seems like an obvious choice.
July 17th, 2007 at 8:53 pm
It’s good to be aware of your driving behavior and mentality, but now think about it from a biker’s perspective! I just love speeding past a line of stopped cars, especially when those cars had been passing me a little ways back. In fact, on my way to work on Monday I biked right by another intern (who was driving) — we were 2 miles from work. To my surprise, I pulled into the parking lot right as he was getting out of his car! Hahahahahaha.
July 18th, 2007 at 8:31 am
I believe most Europeans are surprised by the ubiquity of stop signs here in the US. In many small European towns you’ll be hard pressed to find one stop sign — people simply follow one rule: yield to the right (in addition to ‘have some common sense and be aware of your surroundings’).
Traffic circles are also a good way of letting traffic self-organize (the rule here is to always yield to those already in the circle), and they deal pretty well with varying levels of traffic!
July 22nd, 2007 at 6:34 pm
Leo is right on, roundabouts are much more efficient than stop signs.
Last quarter I conducted some research on driver knowledge of vehicular energy consumption. We asked whether people knew about behavioral options to improve fuel efficiency and if they implemented them. Even though the majority of our sample drove alternative-fueled vehicles and were aware of measures to reduce fuel consumption (the most substantial obviously is speed) they rarely enacted them because they were ‘in a hurry’–the pitiful race you speak of.
It’s not clear if purely transportation-related policies can change behavior in the desired direction since there seem to be deeper sociocultural forces at work. Somehow getting to the root of the problem would be ideal…
July 22nd, 2007 at 10:00 pm
Being a pious driver of a car that has the kind of feedback that you mentioned, there are a couple of additional perks that people tend to leave out. First, I find that I actually drive a lot less than I did with my old car, simply because I don’t want to lower my average tank MPG. The best way to keep that number up there (in my case, about 47-52) is to employ the techniques you mentioned above (plus the “pulse and glide” method used by lots of hybrid drivers) on trips that last longer than 15 or 20 minutes, and have stretches of flat or downhill road. Getting in the car for the 5 minute drive to the store is the single easiest way to lower the tank average. This is because a) it takes the ICE (internal combustion engine) about 5-7 minutes to fully warm up, during which time it is the least efficient, both in terms of mileage and emissions, and b) there’s no combination of road grade (flat both ways, downhill one way) that will give the round trip a chance to click the average MPG up a few points.
The second thing is that hybrids have a unique feel to them in terms of the ICE. When I’m driving less than about 42 MPH, I can usually feel whether the ICE is turned on, and can adjust several things to turn it off and be powered solely by the electric motor. This is something that took a lot of practice, since the ICE is much quieter (and less powerful) than the engine in most cars, but now that I’ve got it figured out, I’m hyper-aware of when I’m actually consuming gas. Of course, this is a feature that’s unique to gas-electric hybrids, and even when running on the motor, there is still an inherent use of gasoline. Still, if you plan your trips just right (taking routes with the fewest uphill stretches and driving with the techniques you mentioned), the amount of gas consumed by the ICE can be minimized.
All of that is aside from the fact that I’m consciously trying to use less gas (I’m a pious liberal, remember?). In general, if my destination is reasonably within walking or biking distance, my (possibly neurotic) desire to have the highest MPG on a tank pretty much keeps me from driving, no matter how lazy I might feel. This used to be true when I didn’t own a hybrid, but I firmly believe that having that little 3-digit number staring me in the face when I get in the car actually makes me consume less.
July 24th, 2007 at 10:27 pm
How did the gas savings of your driving play out? Have you found yourself spending substantially less on gas than you otherwise would?
As far as the traffic circle/roundabout/rotary question, IS there a reason that they’re not prevalent in the US (there are a few in Boston and most visitors from other states hate them)? Safety?