Daniel, anyone lending you money will do a credit check on you. If you have a sound back ground then you'll get whatever deals they have on offer (i.e. you pass the credit check). However, if you're firm with them then they can go back to the finance company and 'haggle' a better rate on your behalf, if you have a good enough credit rating for them to take the risk.
That said, maybe Renault don't do this but it's not illegal practice. Obviously race, sex, age discrimination is...
On another topic.. ISO fix + recaro seats.. Do you need ISO fix in the FRONT? I'm asuming they'll still be in the rear if you order with Recaro fronts?
Rich