The only standardised icon for a boost are coloured chevrons, anything else is not obvious at a glance. Sideways chevrons with the top down car icon would make better use of space, but also indicate a direction which is not the intention.
However, due to bloom issues with some icons I'm providing alternate boost signs, which are just coloured chevrons. If you don't use the actual chevron signs in your track, these are an unambiguous and very clear way to indicate a booster.
Meh.
Last edited by Enai Siaion,