X3 doesn't want to start after left for several days

[MrBrent]

I'm in Vancouver Canada where it is wet and damp these days.
This fall I've found that after I leave the car outside for a few days it does not start easily. I've always managed to start it, but then it runs super rough for maybe half a minute with the whole car shaking. After cranking the starter for a moment, when the engine doesn't start, it sounds like a fan or possibly some electric louvers/flaps being closed in the console which lasts for 5 or 6 seconds. I hadn't heard this sound before during normal operation and don't know what that is about.

Once running it seems fine, and drives ok but in neutral if you hit the gas to rev the engine a bit the tach does not move as ususal, there seems to be some resistance there and it doesn't go as high as you would expect and drops back down quickly. I also find that I'm consuming a lot of oil, ie 1L per 2 or 3 tanks of gas, and I monitor that closely but expect that much consumption is not normal. I use synthetic 5w30. I've had the car for 1 year, and bought it used so not sure how well it was serviced by the previous owner.

Any ideas/suggestions are appreciated,

thanks!

Brent