Petrol - No real difference
Derv - Let the glow plugs do their work before starting the engine. Despite modern derv engines being extremely well build and refinement in the fuel, during really cold mornings (talking daft negative figures here) after your car has been sat over night it could be difficult to start, it is sometimes worth flicking your ignition off and back on again a couple of times after the glow plug light has gone off to give it a bit more of a boost.
For both however, it is best to avoid letting the engine idle for a long period of time. Why? Because engine oil will be at its coldest and wont be as effective at doing its job. Idle does not heat the oil up as quick so this can increase ware on an engine. Best to start the engine, let it idle for a few seconds then set off gently.
Always defrost your windows and mirrors before setting off. Its just dangerous otherwise!
If you have heated windscreen, then use that, otherwise do not use boiling hot water, a can of de-icer or luke warm water will work perfectly well. Top tip: Don't leave your can of de-icer in your car ;)
Aircon works extremely well at demisting a car, however cracking open a couple of windows before getting also helps prevent misting in the first place.
Check your fluid levels.
Generally, coolant should be replaced every 2 years so if it has not been done in a while, now would be a perfect time!
Do they all work? Although they should work throughout the year, its more important with the dark nights. Don't forget to check your fogs!
Are your headlights correctly aimed or do they try and light up the moon? If you don't clean your car regularly, give all of your lights a quick courtesy clean along with your number place. This will improve light output and the number plate clean will stop you getting points and a fine!
Check them over and give them and your screen a good clean with white vinegar.
If they are split or smear even after a clean then replace them!
Avoid using your wipers when your screen is frozen. This will prematurely ware your wipers or cause them to rip/split. Always defrost your windows before operation.
Road salt and general muck is a nightmare this time of year. Ensure you keep your washer bottle topped up with the correct amount of anti freeze. Nothing worse than needing to clean your screen but you find that your washers are frozen up!
Sometimes you may need to defrost your washer spray nozzles so locate them and pour some warm water over them and ensure operation before setting off.
Are they legal (1.6mm over the middle 3/4) and are running at the correct pressure? This is the time of year where you really want the most amount of tread on your tyres. Some people may want to consider a set of winter tyres!
If you have a spare, is it in good condition, inflated and jacks all present and correct?
Old and weak batteries show their lack of strength more frequently during winter months. If you know yours is a bit ropey now might be a good time to get its condition checked and replaced. You don't want to be left in the middle of no where not being able to start it up!