If a slow driver keeps other cars going slower then he is doing them a favor. 45 MPH on the freeway may be pushing it, but sometimes I drop as low as 50 MPH. People can just go around me, so I figure they can just deal with it. In general I maintain at least 50, except when I'm in an exit lane I don't worry about going 45. I'm not going to speed up just so I can slam on the brakes 30 seconds later like most people seem to like to do.
Try your drive next time at 60 or 55 MPH, you'll probably see a major improvement in gas mileage. You say you only spent an extra $2.50, but the truth is over time all those $2.50s add up. You say you waste more than that in your regular lifestyle anyway. Maybe that's true, but if I were you, I'd add that $2.50 to the $3 I didn't spend on Starbucks and I'd already be at $5.50. If you can save $5 a day for a year that's over $1750.
If a slow driver keeps other cars going slower then he is doing them a favor. . . .
Highway vigilantism is not our job. Besides, there are plenty of lower speed options that keep out of the way of others.
When I go into work and am still in warm-up mode, I travel in the far, right-hand lane of the access roads. I often find traffic turning and there are no problems with high-speed tailgaters.
On the highway, I'll look for a truck running at 65 mph and follow them at a safe distance. It isn't hard and the fast traffic just sees the truck. These are trivial and safe solution.
But don't be the sole, traffic obsticle. It isn't safe and there are unstable, road rage warriors out there. Let them by and enjoy the ride.
I don't go slow to be an annoyance to others, but I'm not going to drive faster for them either. If someone is in the slow lane and wants to go faster they can change lanes. I used to feel like "oh, I'd better go 65 not to piss people off", but now my attitude is "screw em". The freeways in my area all have 4-5 lanes, so there's no reason people can't go around, except during rush hour, but then we're all going 15 MPH anyway.
Try your drive next time at 60 or 55 MPH, you'll probably see a major improvement in gas mileage. You say you only spent an extra $2.50, but the truth is over time all those $2.50s add up. You say you waste more than that in your regular lifestyle anyway. Maybe that's true, but if I were you, I'd add that $2.50 to the $3 I didn't spend on Starbucks and I'd already be at $5.50. If you can save $5 a day for a year that's over $1750.
I doubt he'd save anywhere near $2.50 a day, unless he's driving several hours a day. (The value is $2.50 per hour saved by speeding), so it would only really apply as much on longer road trips. Another factor in the mix involves running air-conditioning-- a relevant issue for driving through say the Arizona desert for an extended period. If you spend one less hour on the road, that is one less hour of air-conditioning load. While this won't completely make up for the difference in drag at faster speeds, it will make the average fuel economy for the slower and faster speeds much closer together.
The key though is opportunity cost. On a road trip, especially with multiple peope in the car, it's worth a few bucks a person if whole hours can be shaved from the drive at speeds that are reasonably safe (and secondarily, not likely to be ticketed). However, if you're by yourself on a fairly short commute, it doesn't make any sense to waste the fuel to accelerate to those faster speeds just to brake again later, only to save a couple minutes at most. Also, if you would not have opportunity to do anything useful with that extra time, then nothing is saved.
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Driving faster does save time but it costs more than just gas. Since driving faster might get you a ticket, there is a cost in stress even if you don't get a ticket. Besides the cost of gas you pollute less when driving slow, an additional benefit. Surely driving slower is more safe, to a point anyways. Then there is wear and tear on the car and tires.....
Some good points, though I'd disagree about stress. While I would agree aggressive driving is much more stressful, a conservative driving style with safe following distances at a faster steady speed is no more stressful than at a slower speed. As for the issue with tickets, most of the speeds discussed wouldn't result in a ticket -- on interstates in the open desert, 85mph is the common speed. On I-40 to cite an example I've seen truckers exceeding 85 with highway patrol flying right past them at 90+. (Tucking in behind such a truck's draft at those speeds provides a huge "boost" )
Last edited by Double-Trinity; 07-05-2006 at 10:05 AM.
I've played both games, and now I can't see the point in driving as fast as I used to. Ducking in and out of the left lane while watching for cops and constantly getting on and off the gas may have saved me a few minutes, but was more stressful than it was worth. On the other hand, I don't really enjoy driving 50mph in a 65mph zone, either. My happiest drives are when I'm hanging out in the right lane at a fairly constant speed, just about keeping up with traffic but still getting 40-45mpg out of my "old technology" vehicle through careful application of my right foot and cruise control. There's an FE sweet spot for my car at right about 62mph that keeps aero drag low but allows enough of a speed cushion that I can afford a temporary 2-3mph loss during a coast if a hill isn't as steep as I thought. This also seems to be about the point where the speed differential between me and center-lane traffic is low enough that folks can flow right around if they want to under most circumstances. Those who get "stuck" are generally approaching with 10+mph of excess speed, and often sport a cell phone or other distraction that kept them from changing lanes when everybody else did.
Aside from the gas savings you mention, and the monetary cost of the gas that you didn't burn, and the speeding tickets you didn't get when you were driving slower, you also saved a few other things that I think are important. First, despite Double Trinity's opinion, I agree that 'watching for the cops' or worrying about being caught breaking traffic laws is a stress that I would count as a cost of driving so quickly. Maybe +10 mph doesn't increase your chances of getting ticketed too much in some areas, but in others it really does.
Other things you save when you drive more slowly:
1) Reaction time. You have a lot more time to react to things at lower speeds. This not only helps avoid accidents, but it mitigates the severity of any accidents you do have, because you might just sideswipe something instead of hitting it head-on.
2) Lives. If an accident does happen, accidents at higher speeds are MUCH more deadly. In a collision between two objects, energy is released. It will be transferred from one object to another, and usually some of it goes from one form of energy to another. Looking at it purely as a physics issue, the most important factor in a collision is the speed of the objects colliding, much more than the mass of the objects, because a speeding car has mostly kinetic energy, which is one half the product of the mass and the velocity squared (0.5 m*v ^2). Velocity is SQUARED. That means that something going twice as fast has four times the kinetic energy as it did.
In a collision, all that energy has to go somewhere. Some will be released as noise- squeals, crunches, booms. Some will be released as heat- smoking tires and sweltering bumpers. Some will affect the motion of the other object- you may send pieces of the other car or wall flying in the opposite direction, but unless they're really heavy and go really fast, most of that energy lost when you came to a halt goes into something I'll call 'deformation.' Energy deforms the metal of the car, warps the side panels, crunches the hood, shatters the glass, and most importantly of all, damages the people inside. My mother, who works at a coroner's office, doesn't see too many bodies who were driving 55 on the highway; let's just leave it at that.
3) Car parts. Even if the accident doesn't kill or hurt someone, higher speeds mean much more damage to the car. Remember, twice the speed, four times the energy to do damage.
Not much to add - leahbeatle among others said it well.
5-speed Insight at 40mph: 100mpg
5-speed Insight at 50mph: 80mpg
5-speed Insight at 65mph: 65mpg
5-speed Insight at 80mph: 40mpg
"your results may vary" Different vehicles will tend to show a similar decline in FE as the speed increases...
Like brick, I've steadily slowed down and missed at least a couple of tickets in the process. At 105,000 miles my 1988 CRX HF was on it's 3rd CV boot and needed a new transmission - Insight still has OEM parts on these items. While I consider the Insight's quality better, the overall treatment has been better.
I drive at or under the posted limit as well. I drove to Tulsa and back from Dallas this weekend and got 69.44 MPG at 55 MPH. Every mile I drove, the posted speed limit was 60-75 mph (except in towns of course). I did not drive that speed to alter anyone else's driving behavior or make anyone mad or to teach anyone a lesson. I did it because I want to maximize MPG and minimize wear and tear on my 2005 Prius. One point of interest is that at 55 MPH I was within the minimum and maximum posted limits for the entire trip. More on topic, I averaged 55 MPG on a 2600 mile trip to Florida last month with a 400 lb larger payload at 60 MPH. I estimate it would have been 57-58 MPG at 55 MPH.
Just a thought, but the limits are set for a reason and I don't think it's to incovenience any of us as we drive.
Re: What Can A 15 MPH Difference Do To Affect FE?
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Different vehicles will tend to show a similar decline in FE as the speed increases...
