If you have a car with a blunt type rear door and your rear window gets covered in dirt thatís due to the vortexes.
The degree of dirt is dependant on the cars design.
Itís usually reduced by having a lip above the window at roof level
Every driver that goes on a motorway uses slipstreaming wether they know it or not.
You see it if your travelling in the inside lane and a row of car pass you almost nose to tail. Regretfully there is very little these days of having a cars length between cars of one for every 10 mph of speed.
Mostly I see cars travelling at 70 mph with a gap of about 4 car lengths or less.
The chevrons marked on the A1 (M) between Durham and Chester Le Street are indicators for proper gaps.
When travelling towing my caravan I am generally in the inside lane at about 60 mph. Lorries are usually travelling at the same speed as me. So there forms a sort of tunnel through the air formed by us all but that varies in size due to the type and shape of the lorries as well as the numbers.
This is very noticeable if driving against a headwind. If you pull out to overtake you sometimes are unable to do so because of that wind. Then you may have to drop into a much lower gear than you thought you would.
When you are next on a motorway take note of what it feels like overtaking a vehicle or being passed by a vehicle.
The worst vehicle to be passed by is a transit van type. Because of their shape, size and speed they cause the most disturbance of air.
Iím talking about when Iím towing the caravan, driving solo is different.
Enough from me. Allan C.
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