I came from Coventry (near Ricoh Arena) at 4.30pm today and was dropping off my hire car at BHX Hertz around 4.55 or so. Traffic was heavy-ish on the M6, but moved fairly well, and I walked into the terminal in about 5 mins ...

So, I would say that it's do-able for you ... Particularly since you will be leaving from BAs T1, closest to the Car Parks (?). Could be tight if problems on the M6, but then, that applies on all UK roads !

T2 queues for departures and security screening were bad - 15-20 mins in the queue, but I wouldn't expect T1 to be as bad ...

So I would suggest going for it !! Let us know how it goes.

JP