Feature Suggestion: Custom Date Ranges for Timelines?

[terrapin]

Wondering about the possibility of adding custom time ranges to individual's timelines...

For example, I added a new cap to my truck and I am curious as to what affect that will have on my mileage when it is on versus when it is off.

Another example is, I also would like to track things such as when I add/remove snow tires.

I envisage another text field and a way to add a date -- or range of dates.

Off the top of my head, a few benefits:

* Road trips, etc could be tracked to check mileage on one's vacations or business trips.

* One could check things like cost of operation on a particular trip, which could be helpful for business travelers.

Ideally, these custom time ranges would be visibly on the timeline.

Just a thought. Thanks.