On odd occasions their car services end here (7)
I believe the answer is:
termini
'services end here' is the definition.
(eg a train service ends at a terminus)
'on odd occasions their car' is the wordplay.
'on odd occasions' indicates alternate letters (the odd-numbered letters are used).
'car' becomes 'mini' (Mini Cooper).
The alternate letters of 'their' are 'ter'.
'ter'+'mini'='TERMINI'
(Other definitions for termini that I've seen before include "Starting points, limits" , "Interim (anag.)" , "End-of-line stations" , "Ends, extremities" , "Line ends" .)