Look back on cars: extremely comfortable (9)
I believe the answer is:
reminisce
'look back' is the definition.
(I've seen this before)
'on cars extremely comfortable' is the wordplay.
'on' becomes 're' (regarding).
'cars' becomes 'minis' (Mini Coopers).
'extremely' means to remove the middle letters (only the extremes of the word are used).
'comfortable' with its middle taken out is 'ce'.
're'+'minis'+'ce'='REMINISCE'
(Other definitions for reminisce that I've seen before include "Talk of past events" , "Recount memories" , "Cast mind back over old times" , "Indulge in recollection" , "Have fond recollections" .)