Hello grammer pedants - a or an

[Debbiethemum]

I know you normally use 'a' before words beginning with a constanant and 'an' before words beginning with a vowel. But what if the 'word' is a series of initials.
e.g. Purchase a ML370 or Purchase an ML370
because the M in this instance is pronounced 'em'
thanks

I would say a, though an sounds okay too??????

an ML sounds better .....don;t know if that makes it grammatically correct!

written = a; spoken = an.

Nab3 - I know hence the confusion.
Lulu - Agree an ML sounds better, but we are writing a report so I just want to be grammatically correct.

sorry but lol at grammer

whoops

Is there something like google which tells you how to do this sort of thing? Like an online grammer checker?

Yes - but it keeps on coming up with american grammar (well american spellin)

say "i would recommend purchasing THE ML2345"