From what I can tell, first, you need to find a way to get the RegNo in a uniform format. It seems from the Car table that they prefer to be without spaces.
You could load both tables, then create a new table that links them by loading the comments field and the RegNo field, using a key that is an if statement with the wildcard match.
if(wildmatch([comment], '*[registrationNo]*')=1, [registrationNo}) as KeyField
Definitely it is not a straight forward approach, and you might need little bit of tweaking around with the comment field. Please find attached eg file which i tried might be of any help. Based on my assumption thinking that the Reg numbers in the comment field will be seen after the word 'For'. Taking this as a consideration i have done a workaround.
Let me know if that of any help.
TestReport.qvw 160.0 K
There are several threads here in the forum with similar requests. One of the threads that covers some different approaches is
You may need to create a lookup table with all combinations of registration numbers (i.e. with different spelling, with and without spaces).