OK we are in the middle of the Highlands here and my 2001 Brava 80sx didn't want to know yesterday morning. Eventually the battery gave up with my attempts at starting. Luckily my daughter has a car and was off for the day so i borrowed her Corsa and left for work at 7.00am and it was showing -16 !!
Came home yesterday afternoon and tried it with jumpleads and eventually it fired up after some coughing and spluttering and all seemed well. One of the jaws on the jump leads snapped as the plastic was so cold but still usable.
Out this morning and it fired up straight away then died but there was a hissing sound from underneath the car which slowly died away. Anyway no joy again so the trusty Corsa was borrowed. Came home today at 3.00pm and still minus 11 and tried with the jump leads and after many attempts still no joy and the hissing sound is still coming from underneath the car.

It seems as if there is fuel starvation but too damn cold to do anything. Do you think the fuel lines/pump could be frozen after 2 long nights at minus 16 and the hissing sound is pressure from somewhere.

It's supposed to be warmer tomorrow so maybe it will be happier!

Well she is running again! Tried this morning and no joy, came home from work had a couple of attempts still with the hissing noise coming from below the car. Next try it coughed and spluttered for a while like it was running on 2 or 3 cylinders gave the throttle a blip and then whoomph from the exhaust as something cleared and all back to normal. Took it for a run, got it up to temp and it was purring away nicely.

I can only assume the inside of the exhaust got frozen up and blocked the gases escaping thus the hissing sound which died away. Two nights at minus 16 took their toll however today it is 3-4 degrees and it feels nice and warm!

Thankfully all is well and no nasty garage bill.

Make sure you have proper anti freeze or it will be an expensive fix. Also wd 40 the ht leads and coil pack to rid of damp and help starting

In general, batteries do suffer in such cold weather. Make sure yours is fully charged - if need be using a 230V --> 12V charger. Also make sure your exhaust tail pipe is nice and clear with no rust underneath.