Slipstreaming for better mileage?

umm 65 mph means counting 7 car lengths.



that is what you need to do to be at proper following distance. best not be on the cellphone either... that only increases the time you will need

 

Counting car lengths (1 car length per 10 mph) as a means of keeping a safe distance between you and the car in front will quickly lead drivers to follow dangerously close. Anyone who didn’t sleep their way through high school physics can tell you: A doubling of speed results in a quadrupling of the required stopping distance. Besides that, perception of what is a “car length†is very hard to ascertain at such low angles of views afforded through a car window - and nearly impossible as speeds increase.
http://www.physicsclassroom.com/mmedia/energy/cs.html

The safer method is to maintain a three second delay behind the vehicle in front of you. The amount of space automatically goes up or down with change in speed . . . and there is no real guessing on how long a second lasts . . . (at least beyond how to correctly pronounce Mississippi. )

Both methods are based on the assumption you are following a moving vehicle, have excellent tires and brakes, the driver in unimpaired and paying close attention to the road, and you have excellent road and weather conditions.

Stationary (or kicked-up) road debris is the major failure point of both methods. There is no safe “car length†distance equation for road debris - as it is not moving. At 70 mph, you will travel approximately 154 feet before you even react. And following behind a semi truck at 70 mph with only three seconds will probably only afford you the option of slamming on the brakes. You will hit the road debris . . . and you will likely be rear-ended in the process by someone who was not being as “safe†as you were.

I don’t think there is a safest distance to follow a semi truck. More is better where safety is concerned. Being able to see further down the road and having extra time to calculate your escape from danger is the key. That is very hard to do when most of your view is truck rear end.

 

I really want an affordable distance determiner for the front of my next Prius, if not this one.

Tell me I'm too close, alert me when the gap shortens in case there are no brake lights to warn me. Assisting the cruise control would be excellent.

Radar, sonar, whatever as long as it's legal in all 50 states and Canada, and covers at least a 3-second size gap at 70MPH.

Not to much to ask for, is it?...

 

Highway lanes are typically striped on 40-foot intervals.

Please drive safely