Sounds like he is totally disrespectful.
I don't think there's an easy solution unless you are a master of tact. Unfortunately sounds as if he's already set the bar as to how he's going to treat you as a neighbour.
In an ideal world you'd go round and tell him to sort it but face to face he may just flare up (intentionally or not), a nice letter could do it but might seem like a bit of overkill/strange to him.
The fact is that not everyone loves their cars as much as we do and in this instance I think it's more his mate at fault as he should have said to your neighbour it would be more considerate to cut the wood elsewhere.
I've just moved to a new house so I think I'll try and act hard from the outset to nip anything like this in the bud early rather than let them think they can do whatever they like.
I tried to be nice to a neighbour when we moved everything by going round introducing myself and asking if I could just park the van outside for 5 minutes whilst I unloaded some heavy stuff. I was immediately confronted by NO NO NO! which upset me as I was making the effort!
I've just moved away from a noisy neighbour too which we have tried to settle amicably but he is just an inconsiderate @rse and I'm now hoping he won't hinder my old house being rented out, otherwise I'm going to be financially boned!
Anyway worthless input but just to let you know I feel your pain!