Slow down. My philosophy for life also applies to the road.

[user removed]

Originally Posted by radioranger

As the owner of a Ranger with almost 400 K miles I agree, the trick is to convince others to follow suit. kind of a weird card game wording there. My Dad used to be such a smooth driver it would frustrate me as a teen, i could almost not tell when the car moved or stopped , and I dont ever recall him putting brakes on a car. Course he was a pilot and a boat captain , things you dont usually horse around . His advice was , anybody can drive fast , you've got to be smooth, that's the key. and it's been good advice these 45 years,

Pop once flew a AT6 from Alabama to eastern VA with a gal who hitched a ride. She asked him how he flew the plane when he landed and he showed her how the controls worked. "I never saw them move" was her response to his demonstration. His imputs were so slight that they were not recognizable visually.

He hypermiled his B17 on his bombing missions over Europe in 1943-44, using the mixture and turbo settings to arrive home with an average of 100 gallons more fuel than others. Insurance against bullet punctures in the self sealing tanks.

regards
Mech

[christofoo]

Ever since I saw this data I've been wondering how compacts can be so crummy.
http://ecomodder.com/blog/wp-content..._car_types.jpg
I wish they did better. I don't really want a mid-size, with the exception of the Prius mid-sizes all have 2.2-3L engines, which are blah for MPG.

Of course it is some comfort that speed is more important and slowing down, even a little, really works.

I like the diet soda with burger and fries analogy. I get really annoyed when folks with trucks and SUVs say they want a heavy vehicle to be safer. It's like they never heard of a rollover / can't believe they themselves could ever be at fault.

Because even if you buy into the weight argument, it's a zero sum arms race. Your safety (due to mass) is in proportion to your threat to others. I never hear anyone blame the parents of the drunk teen who decimated a family of six with the 4 ton nuclear weapon they let him drive.

I also really liked the analysis of speed differentials on accident probability and severity.

This part was is a mistake however; "The affect of mass gets divided by two. A 4000 lb SUV will not absorb twice as much energy as a 2000lb car, it will only absorb 50% more."

Energy is linear with mass, so doubling weight does indeed double energy. The one-half term is a scalar, but the function remains linear (and proportional).

Energy is the not exactly the right parameter for safety WRT mass anyway. The key is whether your momentum will be changed by other the vehicle, or you will change the momentum of other vehicle. This follows your percentage of the share of total mass. In the range where your adversary's weight is close to the same as yours, your ability to inflict vs receive is linear with your own mass. Outside of that range the function saturates, and so a 10 ton semi will inflict similar damage on all passenger vehicles, whether they be 2 ton compacts or 4 ton pickups, and 200lbs cyclist will take damage that depends on the height and angle of a vehicle rather than its mass, in any case the victim's final velocity will roughly equal the dominant vehicle's initial velocity.

[JacobAziza]

Originally Posted by christofoo

Ever since I saw this data I've been wondering how compacts can be so crummy.
http://ecomodder.com/blog/wp-content..._car_types.jpg
I wish they did better. I don't really want a mid-size, with the exception of the Prius mid-sizes all have 2.2-3L engines, which are blah for MPG.

I suspect a part of it is that a large percentage of very small cars are sports cars, and by virtue of being sports cars, they are more likely to be driven recklessly, especially (but not limited to) speeding.

This part was is a mistake however; "The affect of mass gets divided by two. A 4000 lb SUV will not absorb twice as much energy as a 2000lb car, it will only absorb 50% more."

Energy is linear with mass, so doubling weight does indeed double energy. The one-half term is a scalar, but the function remains linear (and proportional).

You're right, thank you for pointing that out. Its been a long long time since physics class. I'll fix it.

Energy is the not exactly the right parameter for safety WRT mass anyway. The key is whether your momentum will be changed by other the vehicle, or you will change the momentum of other vehicle.

I know, but there isn't any simple formula to describe that, and in order to make complex concepts understandable to the public (and when I write, I'm more writting to the general public than to hardcore modders) its got to be simplified to some extent.

This follows your percentage of the share of total mass.

not even just that - relative velocities (not just speed, but direction) - factor in as well. A semi-hitting a car causes fatalities at less than half the rate of cars hitting semis, for example, even though both cases have the same percentage share of total mass.

[cujet]

I see your accurate points. But I can't get onboard with your philosophy. In fact, I'd like to go faster! While doing so efficiently.

Klaus Savier, in his Rutan designed Canard Pusher aircraft, managed to get 45 mpg while traveling 207 mph! It's possible to have both speed and economy!

Getting 45 MPG at 207 MPH | Autopia | Wired.com

And now, Klaus has achieved 57MPG at 225MPH. Incredible!

Airliners often achieve over 70 passenger miles per gallon. All while going over 500 miles per hour!

I owned a late model Jetta TDI. While hypermiling was capable of 65MPG, it cost me 4 hours of time per tank of fuel vs driving fast. Or, put another way, my time was worth about $2 dollars per hour. Slow? NO THANK YOU.

[JacobAziza]

Originally Posted by cujet

I see your accurate points. But I can't get onboard with your philosophy. In fact, I'd like to go faster! While doing so efficiently.

Klaus Savier, in his Rutan designed Canard Pusher aircraft, managed to get 45 mpg while traveling 207 mph! It's possible to have both speed and economy!


Airliners often achieve over 70 passenger miles per gallon. All while going over 500 miles per hour!

When personal autos have a co-efficient of drag similar to the most efficient aircraft (0.016, vs 0.35 for a typical modern car - 20 times as much!) then we can speed without getting terrible fuel mileage.

It will still increase the chances of dying in a fiery car crash, though. How many dollars an hour does that translate to?

[cujet]

Originally Posted by JacobAziza

It will still increase the chances of dying in a fiery car crash, though. How many dollars an hour does that translate to?

Not as much a factor as many are led to believe.

First, one's chances of a fatal crash are relatively minor to begin with.

If, you are not drunk, not on the phone, not driving late at night, not under 25 or over 65, your chances of dying in a car are less than flying in an airliner.

I'm a non drinker, I don't text or phone while I drive, and I maintain my skills. I'll take my chances with the slightly higher velocity. (however, I generally don't go too fast either)

[razor02097]

Originally Posted by JacobAziza

When personal autos have a co-efficient of drag similar to the most efficient aircraft (0.016, vs 0.35 for a typical modern car - 20 times as much!) then we can speed without getting terrible fuel mileage.

It will still increase the chances of dying in a fiery car crash, though. How many dollars an hour does that translate to?

yeesh... How many fiery crashes do you see?


I would have to say people going way under the posted speed limit in the left lane are far more dangerous than people traveling at or a little above the posted speed limit.

[DS98HX]

Issue here is that in the area I live, people with Prius are the one stomping off the line and going 80mph everywhere.

[cujet]

As mentioned in an earlier post: Time is valuable. Over a year of driving slow, it's likely 80 additional hours are spent in the car for a typical driver. That's 2 work weeks, lost to the highways. Placing a value on the fuel saved vs. time consumed, it calculates out to be in the neighborhood of $4/hour.

Put another way, my salary is an order of magnitude more than that. Also, my free time is exceedingly valuable to me. It's why I work, to have the funds to spend my time doing what I want.

The performance of an ultra efficient car can be used to save fuel at high speeds. My Jetta TDI returned a solid 42MPG at 80, day in and day out.

Klaus Savier sets all sorts of aviation efficiency records. One that stands out is: 2 people, 45 mpg @ 207 MPH and 60 mpg at 160 MPH. And California to Florida on 26 gallons, in 9 hours.

https://www.wired.com/2009/11/45mpg-at-207mph/

My Cessna 177RG can achieve 25 mpg at 125 mph, if I try. High speed MPG is all about aerodynamics.

[freebeard]

...aviation efficiency records. One that stands out is: 2 people, 45 mpg @ 207 MPH and 60 mpg at 160 MPH.

Time is money is time. This proves the point.

Also "Speed costs money. How fast do you want to go?"