to be honest with you, if i got the results you did i would not try to draft again ever... but thats just me
Yeah I feel the same way. It's more work and I get nervous being that close to somebody. I usually like a lot of space in front of me, like 5-6 stripes, so that I can see around the car I'm following. I just thought I'd try it once.
If you get close enough the rocks will not get up high enough to hit your windshield. Judging distance by the number of stripes . . . anyone know how far they are apart? I usually judge by seconds behind the vehicle and I get some drafting at 3 seconds but much better yet still safe at 2 seconds behind. The savings really depends upon the greater loss in your vehicle - if the engine is burning gas like a pig then air drag will probably not affect the mileage much but EOC will help a lot where as my xB the major factor is air drag since the engine is pretty efficient although it seems to be burning a bit more fuel these days judging by just reving it in neutral. Wind direction would probably have been a bigger factor on your trip.
The time you usually get a rock tossed up is when they change lanes. The sand and rocks usually settle onto the striped lines between lanes and the breakdown lanes on either side of the road where the winds of passing cars usually move them. So as long as they stay in the center of the lane infront of you there are few if any rocks being tossed up. The more important thing to look for is proper mud flaps on trucks and long tails on cars and SUVs in front of you. Get behind a Jeep or any vehicle with high ground clearance and a short trunk or any vehicle that you can see half the tire showing from behind it and you can bet it will be throwing up stones. A high performace car with sticky tires is another thing to watch out for - I have had them throw rocks from the next lane as they pass since usually their tires are too close to the outsides of their wheel wells.
Wind direction would probably have been a bigger factor on your trip.
Yeah I had thought of that, too, but it was only a very slight crosswind (2-3 mph I think) for the whole trip. However, here in Kansas it gets pretty darn windy. I can imagine drafting into a headwind helps a lot, a tailwind not so much, and a crosswind.......??? I suppose it depends on the speed of the crosswind and how quickly it erases the wake behind your host vehicle?