Sports car in a large Somerset town keeping acceleration at zero (4,5)

'sports car' is the definition.
(I've seen this before)

'a large somerset town keeping acceleration at zero' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'somerset town' becomes 'frome' (I've seen this before).
'keeping' means one lot of letters goes inside another (some letters kept inside).
'acceleration' becomes 'a' (symbol used in Physics e.g. f=ma).
'at zero' becomes 'o' (I am not sure about this - if you are sure you should believe this answer much more).
'frome' going around 'a' is 'farome'.
'a'+'l'+'farome'+'o'='ALFA ROMEO'

'in' is the link.

Can you help me to learn more?