Quote:
Originally Posted by bestmapman
I would like to know if anyone thinks it is possible to make/modify a car to get 200 MPG on the highway.
Here is the specs:
1000 miles unrefueled range
65 MPH average speed
Other than those specs, sky is the limit.
|
I have some formulas that would help to figure out what is required to do that. Here are two useful ones:
MPG=2343.75/(BSFC*F)
P=F*V/375
We can guess that the BSFC will be about 0.5 lb/hp*hr and we know that the MPG=200 so I'll rearrange the first formula to determine F (force in pounds).
F*MPG=2343.75/BSFC
F=2343.75/(BSFC*MPG)
F=2343.75/(0.5 * 200)
F=23.4375
Now I can calculate horsepower from F and V.
P=F*V/375
F=23.4375 LB
V=65 MPH
P=23.4375*65/375
P=4.0625 HP
I heard on the radio that a Ford Taurus has such low drag that it requires only 21 HP to go 65 MPH. The 200 MPG car needs to have its total drag reduced to less than 20% of the Taurus. This would require a very small frontal area, low coefficient of aerodynamic drag, light weight and very easy rolling tires. It should be possible. There are some streamlined bicycles that can go 60 MPH on about 1 HP of human muscle power. It should be no big problem to adapt to engine power and go 65 MPH on less than 4 HP. Of course the car would have to have a much smaller than normal engine. A one cylinder engine with about 200 cc (0.2 liter) seems about right for making 4 HP efficiently.
I found some pictures of a streamlined bicycle here:
Coslinger special HPV streamliner recumbent bicycle
Here is a graph of MPG vs speed for super efficient vehicles:
Super-Mileage Vehicle Fuel Economy as a Function of Speed