Fast vehicle ditched by Shell? (5)

I believe the answer is:

apace

I'm a little stuck... Click here to teach me more about this clue!

'fast' is the definition.
(apace can mean quickly)

I don't understand how the remainder of the clue works.

(Other definitions for apace that I've seen before include "flat out" , "(Move on) swiftly" , "Swiftly, quickly" , "Quick" , "At a rapid rate" .)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app