Quote:
Originally Posted by NoCO2
.... <snip> This, obviously doesn't work if your only going 20mph because 1 car length is just flat out too close, but, 3-4 car lengths still gives a pretty decent FE gain <snip> ...
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The nature of drafting (about which I've blogged quite a bit) is such that drafting at 20 m.p.h. is pretty worthless anyway. The faster you're going, the more it helps, BUT if it's too fast, the relative gain in drag reduction is more than offset by the loss in fuel economy due to the speed regardless of the drafting.
In my LR3 which I drive at 55 m.p.h., using data from the scan gauge and some experimentation, I calculated that if I have to exceed 59 m.p.h., my fuel economy is reduced. Finding candidate drafting vehicles is very difficult. I'm able to find one well under 5% of the time I'm on the freeway.