I find myself thinking about car lifetime weight MPG penalty Topic is solved

[volvolugnut]

Car fuel economy has many factors. At speeds under about 50 MPH, the rolling resistance is the main factor. Rolling resistance is the friction between the tires and the road. Smooth, hard roads and smooth, hard, over inflated tires will have the least rolling resistance. The total rolling drag will be the rolling resistance times the total weight. But smooth roads and tires do not grip well for turning and braking. Basic sliding/rolling friction physics.
At higher speeds air resistance become the larger factor in drag. Air drag is product of frontal area, drag coefficient, and velocity squared. Modern cars often have better drag coefficient (slippery).
Fuel economy will depend on the rolling resistance plus the air resistance and the efficiency of the engine and drive train. Lighter oils, lower engine speeds and fewer rotating parts will help drive train efficiency. Gasoline engines get better fuel economy when running hot, and lean, with high compression ratio. But these factors are not all good for engine life and clean exhaust.
volvolugnut

[abscate]

I admit I thought the Segway (Kamen's invention) was going to change cities.

I think he forgot the human factor. Knocking over Segway riders with a shovel was just too tempting in the Northeast, at least. My highest weekly score was 11 , which was record for a few years.""

[volvolugnut]

Yes, there would be considerable added drag from the momentum loss when the moving shovel hits the relatively slow Segway rider. Any type of road kill would be a drag.
Especially large animals.
vovolugnuty

[BlackBart]

For a while, every campus security cop was on a Segway.

[abscate]

Here was my swag

100 kg is about 5% of the car mass

The frictional force is the normal force times the mass, so the frictional force goes up 5%. The frictional force is about 1/3 of the total force acting to slow car , so net effect 1.5% on mpg

There is an additional energy penalty for kinetic energy, important in city, less so on highway

[matthew1]

Bingo

bingo.jpeg (60.65 KiB) Viewed 291 times

[volvolugnut]

Ken mansplains to Barbie.

volvolugnut

[pgill]

Matt,

The auto manufacturers are constantly looking for way to improve fuel efficiency.

And the consumer is always looking for more luxury and power.

There forces are working against each other.

Here is some information from our friends to the North

Weight reduction
Estimated fuel cost savings
over 200 000 km
------------Cars Trucks
10 kg----$104-----$130
25 kg----$260-----$325
50 kg----$520-----$650
100 kg---$1,040----$1,300
200 kg----$2,080----$2,600
400 kg----$4,160----$5,200
1 000 kg---$10,400----$13,000


Switching to units that make sense to me

2,200 pound increase will cost you $10,000 to drive 125,000 miles which is about 10 years of driving for a typical American.
So $1000 per year.

autosmart_factsheet_16_e.pdf

(418.81 KiB) Downloaded 2992 times

Take care

Paul

[matthew1]

Brilliant pdf, thanks Paul. I suppose I might be more sensitive to this than residents of other cities (or rural), because it seems half of everyone driving has a Tacoma or Jeep with all this stuff on it. So many 20-30-somethings move here every year. Colorado! Camping/Skiing/Snowboarding/Weed/Stand up Paddleboarding/Canoeing/Fishing/Biking... it's catnip to these young kids, and I don't blame them to be honest.

They buy cars for the lifestyle promise, but I really know deep down that 95% of the time these people are just driving to or from their 9-5 job... commuting. I see them weekday mornings and afternoons when I take my son to and from school.

And the consumer is always looking for more luxury and power.

There forces are working against each other.

And safety... which is why small cars today get only roughly the same MPG as small cars from say 1985, despite the enormous gains in fuel efficiency as it applies to engines. The difference is small cars today weigh 3000 pounds, and small cars from 1985 weighed 2000 pounds. A lot of the weight gain is for safety.

Remember when you could see really well out of cars because they had lots of glass and thin A and B-pillars? No longer. Doors are tall and strong, and pillars are like house foundation 4x4 inch boards.

[volvolugnut]

Matt,

The auto manufacturers are constantly looking for way to improve fuel efficiency.

And the consumer is always looking for more luxury and power.

There forces are working against each other.


Paul

I think you nailed it, Paul. We complain about fuel economy, but we buy performance and features. I have owned and driven cars that got near 40 MPG, but they were not very comfortable, roomy, or had anything to call performance.
My main drivers today are comfortable, roomy, have more than enough performance, and get about 25 to 28 MPG. These are a 4 door sedan MB E320 and Volvo V70 T5.
Guess I have made my choice.
volvolugnut