In case it got overlooked, I did post sometime in the last couple of days that the determination of the age of bloodstains is notoriously unreliable. There may be a brand new wizz-bang test that is highly accurate that I don't know about, but the last time I heard (and that was VERY recently) it is extremely difficult if not impossible to age bloodstains once past the first couple of hours or so. Actually - I'll check again in the next day or so - I have my sources....
I would imagine that the defence may be planning on using that fact to claim that the bloodstains in the back of the car were from an earlier date, and perhaps from something like a nosebleed.
Just an opinion, as always