|
Instead of looking at the grand-unified-theory of hypermilling/ecomodding how about looking at each individual mod and trying to estimate it's economics. I'll start with EOC into lights vs. wear/tear on starter.
Average vehicle drives 350 days a year to/from work and weekends. So 700 starter motor events. Because sometimes you stop at the bank/grocery store lets say 1000.
I've had starter motors go out at 15 years up to never so say 20,000 is the average life of starter motor.
So my commute I have 4-6 lights that are long cycle so on average commute I may EOC and restart 3 more times. 6 times a day 250 commuting days a year = 1500 extra starts a year. So my starter is used 1000 normal starts + 1500 extra starts expected life = 8 years. So in a 20 year life expectancy of a car I have to replace starter motor twice at 200 dollars a pop = 400.
Now I would not EOC into a light unless I know I'm going to be there more then 10 seconds. Sometimes 15secs sometime 1 min. Lets say average not idling is 30 seconds.
So 6 times a day at 30 seconds a day at 250 commuting days a year = 750 minutes a year. My GPH at idle is 0.2 so I save in a year 2.5 gallons or $7.50.
Not nearly enough to buy/rebuild a starter every 8 years just based on gasoline costs.
But I still do it. It is not rational. We are not rational people. There has to be some other factors that can't be measured or quantified at play to get me to make this completely irrational decision.
Sure you could argue that one or more of the above assumptions is off. But you would have to really work the numbers to get to a point where EOC'ing into a traffic light is ever going to save enough gas to buy a starter motor. It would be more then doubling GPH or doubling wait times or 50 dollars for rebuild starter motors. (Invite all the engineers to check my math on there own time)
|