Quote:
Originally Posted by basjoos
An easy way to determine your car's aeromod potential is to note what your mpg is when drafting another vehicle. This is the mpg that you could get if you thoroughly aeromodded your car to reduce its Cd.
In addition to improved mpg and the equivalent of a horsepower boost at higher speeds, two side effects of reducing your Cd is that drafting has less effect on improving your mileage and the non-fan assisted air flow through the ventilation system is diminished. Both of these require the presence of a high pressure zone at the front of the car and a low pressure zone at the rear of the car to manifest. As you lower your Cd, you reduce the pressure differential between the front and rear of the car.
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I've drafted behind some trucks, but not particularly close. The problem is that I've never done it at my normal driving speeds, so I can't really tell how much if from the speed reduction. I have noticed that I get a better draft off of a flatbed truck than off of one with a big box. Particularly if the flat bed has some random items placed on it to really disturb the air.
I once drove behind two or three trucks (mini convoy) just to see what would happen, and at 60-65mph behind them I got somewhere around 70-75mpg. It was not well documented, but was an interesting trip. Felt like it doubled my time to get to the customer, but was a good experiment.
For this drafting test, do you mean finding a friend with a car and following very closely, or just following somewhat close to any vehicle, or are you talking about following trucks?