GR - as i understand it.
a POLISH is used to actually make your paint/clear-coat shine, by using very very small abrasives in the polish to remove the old dead top coat, kind of like exfoliating your skin whihc makes your skin glow. With a good polish the micro-abrasives break down as they are "rubbed" into the paint which caused an even finer polishing action.
Once your car is gleaming a WAX (which shouldnt be abrasive at all) is used to put a protective coating over your newly-polished and shiny surface. Any surface contaminants which come into contact with your car actually make contact with your wax barrier. As the wax slowly wears off, through vehicle washing (especially with some shampoos which actually strip off the wax) and through exposure to the elements, you should wax your car again to continue to protect your surface.
Eventually, you will need to POLISH your car, but this shouldnt be done every time you wash your car, because, like ive said removes a very fine top layer of your paint, but a good quality wax, like your hubbys zymol is fine to use as often as you like.
An example of a polish is Autoglym Super resin Polish. If you were to use this on a red painted (not clear-coated) car for example, you would notice the applicator starts to turn red - this is the top surface of the paint coming off. this is what a polish is supposed to do. The autoglym also contains a wax additive too i believe which gives you your wax protection.
meguairs produce a 3-stage car cleaning/polishing/waxing system.
Stage 1 in a cleaner system (similar to a lot of normal polishes), which removes all of your surface contaminents and swirls marks - like a body scrub for your car.
Stage 2 is a pure polish (not a wax) that actually conditions and nourishes the paint, which gives you that lovely, deep wet shine.
Stage 3 is a carnuba wax which protects the finish you have just created.
Obviously, not everyone can/be bothered to spend a lot of time prepping their car, and so a "cleaner/wax" (like the autoglym polish) is ideal for them. BUT it will strip off your finish, which as we now, on renaults isnt very thick or hard as it is.
Anyway, GR, i thought you were the cliosport car-cleaning guru it worth checking out www.meguairs.co.uk as they seem to offer a pretty comprehensive range of "proper" car cleaning stuff. pop and have a look.
Next weekend, the autoglym roadshow is coming to my local shopping mall, doing demonstrations for both days, so im gonna pop along and try to pick up some more tips.
See ya
Face