[Jt martin]

In some spots on the Highway, you often can drive beside concrete walls. Is it adventitious to drive near these concrete walls in order to reduce aerodynamic drag? I have to imagine that the front of your car is pushing air away from the vehicle and into the wall which may reduce overall aerodynamic efficiency. On the flipside, I know that in racing driving at the wall can increases speed. So, the question is, should you drive near the concrete wall or not?

As a second question, is it adventitious to drive beside a larger vehicle? I know that if you have a crosswind, using a larger vehicle can help reduce the negative effects of that crosswind. With this not being a factor, does driving beside a larger vehicle give you an advantage? I know larger vehicles have a tendency to suck air in near the rear of the vehicle, and push air out at the front of the vehicle. I would imagine the vacuum would be the place that you would want to be for maximum efficiency. Is that the case?

Thanks, guys.