After tire pressure, here's the easiest place to start: the Micra has one heck of a gaping maw for a little car!
The box with the diagonal lines is where the radiator is; the orange area is wide open grille, where many cars these days have at least
some blocked "faux grille" sections.
Interestingly, the Versa Note, which uses the exact same 109 hp engine/trans (manual, but not the automatic) has blocked off "faux grille" sections, plus it uses active grille shutters on some trims. (Tried, but failed to find a pic of them.)
Considering this Micra has a manual trans and has no A/C, its cooling requirements are bottom of the ladder. There's absolutely no need for this much flow-through in normal circumstances.
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Casting your attention a little lower in the photo, note the absense of either an air dam or tire deflectors (front or rear). The Note, on the other hand, comes with what looks like about a 2-3 inch air dam, plus deflectors ahead of the rear tires.
Drag coefficients:
- 0.315 Micra
- 0.298 Versa Note (CVT)
For comparison, note (HA, pardon the pun!) the Note's faux grille sections (1 larger, lower; 2 smaller upper) and the air dam:
