AH! So is that why W3W bulbs are a smaller size than W5W?
I think those are the DRLs as headlight bulbs in a Prius would be H4 (or a simular Hi/Lo combo bulb)
W3W and W5W are the same size. Only difference is the filament.
Prius uses an H11 and H9 bulb. The high and low beams are separate.