I had to keep the car outside on a recent ski trip where the temp dropped to -15 each night. Couldnt get it going in the morning. Just got it running late afternoon ( -7) and got home OK.

What do I need to do to ensure it will run like all the other French cars in resort in these temps?

If it's a diesel car, make sure the fuel is meant for use in a cold climate (fill up the car in the area you are going to stay)

"Summer diesel" will wax in low temperatures, and your car won't start!

and possibly invest in an engine preheater, basically just a heating element in your coolant, put it on a couple of hours before you go out

We have diesels out here living all winter out in the cold. Just use winter diesel, make sure the antifreeze and battery are up to spec and treat the door seals with some nice silicon based something to prevent them from sticking.

The lowest I've been with my petrol Octi has been -23 for a week, and apart from having to dig it out of 1ft of overnight snow once you couldn't tell any difference.

-15 isn't cold. There's something wrong if your car won't start at those temps.

Thanks

I'm wondering that there might be something wrong other then the temps (although alot of cars were struggling).

Certainly she starts fine as a rule, but then when warmed up, stoppped and restarted does not easily fire up.