Unfortunately you can't do simple arithmatic within the DashXL Editor to convert kPa to bar but I do have a solution for you.
All you need to do is write a very simple script that takes the metric value from SAE.FRP_C and divides it by 100. You would then use the script as the PID in the dashboard.
For example, a script called SCRIPT.FRP_C_bar would be:
and you would use SCRIPT.FRP_C_bar in DashXL editor instead of SAE.FRP_C
Obdii.PidValueMetric = Obdii.PidValue.GetDataValueMetric("SAE.FRP_C") / 100;
Obdii.PidValueEnglish = Obdii.PidValue.GetDataValueEnglish("SAE.FRP_C");
You need to create the script in ScanXL (an unregistered version works fine) then export it. You then need import the script into the latest version of DashCommand.
BTW allowing simple math on PIDs with a dashboard is on our 'to do' list but until then using scripts is the only way.
Hope this helps.