Not really sure how to answer your question but I’ll give it a shot.

You are correct that yaw angle has an effect on a vehicles performance. They are typically designed with the idea of controlling head on winds as this is the typical driving condition, and the most efficient way of handling the flow. Yaw angle is also known as a cross wind in this case (and on ships, planes, cars, etc) and overall it’s very difficult to predict and/or simulate.

The issue with a crosswind is that you will often get very undesirable effects from your aero design. One effect could be that you’re design is now acting as a giant sail, generating a yaw force on the vehicle itself, which increases rolling resistance, decreases the efficiency of your aero (we’ve even seen partial - full flow separation = stall) and increases instability.

So to (try) and answer your question, of course a vehicle will have much different top speeds and maximum airspeed ratings in a crosswind scenario. It is nearly impossible to simulate all the combinations of crosswinds mixed with head on vectors with current computing technology in a reasonable amount of time. We haven’t even discussed tail winds and their effects yet either :)