You can view card-specific stats through the Lead and Cycle Time diagram. It will provide you with a start time, an end time, and a cycle time statistic for each task.
Another good piece of card-specific information is the Time log, accessible from the task itself. It shows how much time different users have spent working on it.
Information on working time entries for specific tasks can also be read from the Summary View of the Time Report, after grouping entries by task and by user together.
Note: the Time Log and Time Report are only available on the Enterprise plan.