A 1.25 fiesta isn't that slow, granted you're not gonna set any sub 10s times doing 0-60 but then no suitable first car will.
I'll agree with you on the corsa and chav thing, but if yours isn't kitted out then you aren't going to look like them. Fiesta's though are just common amongst all people, yeah you see a few 1.3's encores with big alloys and spoilers but you see more being driven by everyday people.
Chavs get their mitts on all the suitable first cars, remember that insurance money saved goes on undeclared mods. But luckily they butcher them so you only become associated if you follow suit and make those tasteless mods.