When using the "Multi Dial" HUD/theme, the icon displayed when you've requested a pitstop is a Black Wrench in the upper-left corner of the screen. But in some of the closed-cockpit cars like the Nissan 370Z it is difficult, and sometimes impossible, to see this black wrench because it does not contrast against the inside roof and/or roll bars in cockpit view. Perhaps give the wrench an outline of Yellow or White so it is able to be seen even against a black or very dark cockpit interior.
