@Rl8x 

So you are saying your 'H' config is better than the 'V' for distance?

 being the 'V' config and you can see the 90' between the two antennas.

You can rotate the antenna base collar so the antenna knuckle is oriented so that the dipole is easily bent the correct way.

Those look like some pretty solid walls...so you're likely to only get decent RF performance straight back from the antenna..ie along the driver side of the vehicle.  If there is a similar wall on the other side, then you've created a 'waveguide', basically forcing your radio signal along a narrow path off the face of the antenna.  RF doesn't like to go around corners, so unless there's something solid behind the vehicle to reflect the waves, you could have a pretty narrow coverage area.

If you do you speed test, using 5.8Ghz band, walking straight back from the AP (while keeping a clear line of sight to it) what do your speeds/signal strengths look like at 5, 10 and 20m? 

  @Rl8x 

Ok not unreasonable on the 5.8.  If you switch your testing to the 2.4G band, and test from the location (or closeby) the location of your IOT devices/sensors, how does the performance compare?

Are you using the same SSID as you use inside the house (devices could be flapping between APs).  You could try a unique SSID only assigned to the carport AP and only active on the 2.4G band.

How congested is the local 2.4G band out by the sensors?  If you have an android phone/tablet, then WiFi Analyser app does a good job of reporting the local RF scene.

  @Rl8x I honestly think you have an issue with the 2.4G radio in that unit (or the internal wiring to/from it).  It should perform much better than what you are reporting.

Are you able to do a warrantly claim/order another?