| | Re: Explain this sentence
Interesting - this appears to be spoken English (eg the punctuation is inappropriate for written English) and so as if the listener could interrupt to ask the speaker to clarify ambiguities, which do frequently occur in spoken English. The speaker/writer is saying :
a) It is not essential to keep the car in gear whether on flat ground or a hill but...
b) If you keep the car in gear, it prevents problems if the handbrake fails
c) Therefore I personally would keep the car in gear wherever I was.
Hope that answers your question.