40 isn't too bad on a bike. Not real comfortable, but not too bad. The first day out on Dr.Linda's new bike, with only 7K miles to get home, it was 40F and pouring down rain on Canada.
I once rode from Central Texas to the PRC, and it never got above 15F until I hit the California border. On a shovelhead, yet. That was a bit cold. I'd ride a while, stop and thaw out at the anti-freeze dispensary, ride some more. I could only make 500 miles a day.
I once changed out a starter on a MB 220D in Iowa at Christmas/New Years. I think it got up to 5F or so. That was some cold wrenchin'.
We had 2 inches of snow last night. Temps almost up to freezing today. Gonna be cold this week.