This is a Mk1 Fiesta. It has vertical tail lights with (optional) reversing light under the bumper
This is a Mk2. It has vertical tail lights but they now incorporate a brace of reversing lights. The by now compulsory rear fog lives under the bumper.
This is a Mk3. It has vertical tail lights. The rear fog light now replaces one of the reversing lights, as it has done since. The rust was not standard.
This is a Mk7. It has vertical rear lights. You may note a trend here.
This is a Mk8. You’ll see a difference. Horizontal tail lights. Ford’s stylists have concluded that horizontal lights impart a sense of greater width than vertical ones so the car looks bigger. Note that the number, VTH 818, can still be read (as 818 HTV) if you reverse the picture. Ford do this with most of their official demo cars.
They’ve done the same with the Focus incidentally.
So there we have it. To impress your customers with a small car, go horizontal. Personally I think the Mk8 looks bland but who am I to disagree with the assembled might of the Ford Motor Company?