Once you do get the car on the road, a useful aid for the long term is a chart or table that shows ambient temp vs glow time. Since each 220D will be a bit different, this is something that you will have to create using experience over the course of a year. Thankfully your winter temps are probably not very severe, and won't stretch the table out to infinity!!!

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150