If all cars had trailer hitches, could you move more cars with less fuel?

Question

If cars hitched up to each other (say 4 cars) and only the lead car was turned on, how many fewer gallons of gas would it take to move the 4 cars 100 miles than if they drove themselves. Assume each car gets 30mpg on their own.

Answer 1

my truck gets 20 mpg.

when i tow my race car trailer (10,000 lbs or 2.5 to 3 cars equivalent) it drops to 9 mpg.

so if the 3 cars get 30 mpg, 3 gallons will get 90 miles of travel.

my truck towing them will get 27 miles for the same 3 gallons

Answer 2

Probably, but what would you do when someone wants to go their own way?

It would at least reduce the effect of wind like a race driver "drafting" the lead car.

Answer 3

ya, there are specil cars for that. If ur car is a deisel user then it would be realy hard to use less fule and not distroy the enviorment....

Answer 4

Yes you would use less fuel over all. Assuming that one vehicle was able to tow three times its own weight without serious damage.

How much saving would be determined by the shape of the vehicles used.

Crash course

The energy used by any vehicle is to overcome three factors (in order of significance at highway speeds) wind resistance, rolling resistance and drive train inefficiencies. If it did not have air to push through or rolling friction, it would continue at a given speed indefinitely.

In this case

Four cars (joined nose to tail) would have the frontal area of one. But the drag coefficient would be higher. The wind would not flow as smoothly over all four vehicles. (Though a lot better than four separate vehicles)

The rolling resistance would be about the same (weight of hitches negligible).

All the energy saving would be from reduced wind resistance overall and loses in one vehicles drive train only. It would be worthwhile noting that if the energy where supplied from all four vehicles the drive train losses would wind up about the same.

I recall a precision driving team doing a nose to tail experiment with four cars, some time ago the average consumption improvement was 50%

i.e. all vehicles would have averaged about 45 mpg if 30 on there own.  

Of course the first vehicles consumption was about the same (a little less tail drag). Then continually improved consumption to the last.

With the absence of data for rolling resistance, wind resistance and frontal area this is as good an answer as I can give you.

These links will give the info required to calculate reasonably accurately.

http://en.wikipedia.org/wiki/Rolling_res...

http://en.wikipedia.org/wiki/Wind_resist...

Answer 5

a car that weighs 2100 pounds may get 30mpg but if a car that weighs 2100 and pulls 6000 pounds will not get 30 mpg around 8 mpg and would need a new set of brake pads every 2000 miles and would be very hard to turn and hard to change lanes

Answer 6

If you only towed one car you might get better than half the fuel economy but if you towed several cars the added weight would make it a poor choice.

There are better choices.