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> Projecting these results to all drivers nationwide [US], 255 million drivers made a total of 227 billion driving trips, spent 93 billion hours driving, and dr

by jpc0 2y ago

> Projecting these results to all drivers nationwide [US], 255 million drivers made a total of 227 billion driving trips, spent 93 billion hours driving, and drove 2.8 trillion miles in 2022 I don't have a dog in this race but I want to spark conversation. I feel like assuming that saving 1% of those drivers time would lead to an increase in productivity, possibly a tiny increase in happiness but are you happy now driving 20 over the limit and on high alert all the time during your commute? Generally I am less tired going 100 km/h in a 120 than I am doing 140km/h in a 120 for the exact same trip... And usually I would just move my commute a bit, have breakfast close to work / at work and hit the gym after work at work and you significantly cut down your commute time... It also reminds me just a little of Brook's law... I'm never going to believe a car is more fuel efficient at say 35 vs 50... Maybe 25 but where are you driving that the majority of your trip is at 25? The few minutes you spend at 25 won't even put a dent on your efficiency numbers if you have a reasonably long commute and if you don't what the hell are you complaining about. At least where I am 25 would only be used i residential areas or places where high pedestrian activity is expected... The limit is almost exclusively 35/50/75 and you may get 60 in rural areas...

toast0 2y ago
I haven't watched numbers on many of my cars, but my Jetta SportWagen TDI had peak mpg right around 60 mph, at least it did when I had steered the wheel at all since startup ;). The gear ratios are setup to deliver peak efficiency at highway speeds, although you do hit a point where the v squared in drag wins. EV is different, because motors are strictly worse the faster they spin. Vehicle provided instant MPG data is always a little suspect, of course.
- jpc0 2y ago
  Ah so that is kind of the point I wanted to try and make. The engine isn't any less efficient in lower gears. It's just that you are measuring MPG and not some other metric like hours per gallon. If you are able to travel at 60 the entire time then sure, but at the same RPM your engine is consuming the same fuel in a lower gear. I'm pretty sure that MPG value would also very aggressively change if you were constantly accelerating and deceleration to hit that 60 MPH number whereas it would in fact have been more efficient to travel at a lower constant speed.

by jpc0 2y ago

toast0 2y ago

I haven't watched numbers on many of my cars, but my Jetta SportWagen TDI had peak mpg right around 60 mph, at least it did when I had steered the wheel at all since startup ;). The gear ratios are setup to deliver peak efficiency at highway speeds, although you do hit a point where the v squared in drag wins. EV is different, because motors are strictly worse the faster they spin. Vehicle provided instant MPG data is always a little suspect, of course.

jpc0 2y ago
Ah so that is kind of the point I wanted to try and make. The engine isn't any less efficient in lower gears. It's just that you are measuring MPG and not some other metric like hours per gallon. If you are able to travel at 60 the entire time then sure, but at the same RPM your engine is consuming the same fuel in a lower gear. I'm pretty sure that MPG value would also very aggressively change if you were constantly accelerating and deceleration to hit that 60 MPH number whereas it would in fact have been more efficient to travel at a lower constant speed.