I have the NAVI. Can't help you with the clock.
CX9s NAVI system has the clock from GPS satellites.
It is 100% accurate. (one side benefit that people don't think about)
For trip computer, there were only trip meters, no trip computer until 2009 model.
I have the ScanGaugeII-X mounted behind my steering, and in front of the odometer (block it a bit).
One of the THREE functions is being trip computer.
The other two are:
Gauge: see operating conditions of your vehicle (coolant temp, intake air temp, battery voltage, RPM,....)
Scan: see error codes (knock on the wood), and reset them if you need to
See manual and installation PDF here
http://www.google.com/url?sa=t&rct=...9cC4Cg&usg=AFQjCNFkcBRN69ZT8g1TGRa8voTMAO6Q_w
The ScanGaugeII-X is much more than a simple trip computer, and it is portable to your next vehicle.
BTW, the "-X" stands for an extension that allows programming into Prius' OBDII system. That is not needed for CX9 owners, but my wife has a Prius.
The cost was around $160 when I bought mine from eBay. It is cheaper now since there are more alternatives.
Here is one on eBay:
https://www.ebay.com (commissions earned)
Be careful not to get the original ScanGauge (w/o -II or -2 in the description), which is cheaper and has fewer functions, I believe.