It is an arithmetic expression, i.e. sequence of numbers/variables separated by operators like +, -, *, /. Typically you would use it to compute values such as monthly mileage, e.g. 18.5 * duty, where duty is the sum of the on-duty trip distances for the month.
What is a variable?
You can define one or more variables to be used in an expression. The benefit of using a variable instead of just putting a hard coded numeric value in an expression, is that you can change the variable’s value for each month. For example, you need to compute the fringe benefit tax of free fuels, then you can update the fuel price for every month and do not need to change the expression formula. That means, when you browse from month to month, the computed value will be dependent on the fuel price you have entered for that particular month.
Can I generate a report in PDF/XML/CSV?
Not yet, but we are working on it.
Can I export all my trip data to the SD card?
Not yet, but we are working on a CSV format that can be used for both export/import from the SD card.
Can I import trips from a CSV file on the SD card?
See the answer above.
What is Flurry Analytics?
It’s a tool to track anonymous usage statistics for smart phones, like Android, iPhone, BlackBerry and more. We are using flurry to track
Session length
Creation counts for trips/expressions/variables/reports
Errors
Course-grained geographical position. like city/country
No more paper trail, when driving on-duty 
