Airspeed indicator for your car

[basjoos]

Based on the effects on my coasting car as a semi-truck slowly passes me, I get a slight reduction in drag when the front of the truck is just behind my car in the adjacent lane, but there is a significant increase in drag as the truck is running alongside me, and then there is a noticable drag reduction as the rear of the truck pulls ahead of the front of my car.

The heat associated with an aircraft's pitot tube is to prevent ice from forming on and clogging the tube while flying in icing conditions. Typically there is a switch in the cockpit that turns on the pitot heat.

[basjoos]

krousdb, since the static port of your airspeed indicator is inside your car (and inside your ventilation system based on your description of ASI's location on your dashboard), what effect does running the ventilation fan and/or opening the windows have on your indicated airspeed? On aircraft, the static port is typically on the side of the fuselage so that the indicated airspeed would be unaffected by window or air vent activity.

[krousdb]

Yes, I was concerned about that also so I did a test to see if there was an effect. Cruising at 30 MPH on a calm day, the gauge also shows 30 MPH. Turning on the vent fan at full speed had no effect. Nor did opening a window.

Another note.... I tried moving the pitot tube into the bumper further so it became less noticeable, leaving it protruding only by an inch. This caused the ASI to under register by about 1/3. I moved it back to 3" protrusion and it registers fine again.