They should fit with speaker adapters which you can make from MDF or buy which will be made from plastic.
Focal make a 8inch version for our cars ISS200 so you can put these in your front doors and the is165 in your rear door.
How good of an upgrade they will be I'm not sure as I've not heard them, but Focal are a good brand.
As these cars do rattle quite a bit what you also need to do is sound deadening on the doors.
I'd actually try this route first as sound deadening will make a lot of difference and will make the original speakers sound much better and who knows you maybe happy with the improvement.
If you do upgrade your speakers they will be pushing more air and they may actually sound worse with all the vibrations/rattles etc