I think the answer is to have buzzards either use the zombie walk/run speed setting (adjusted to their pace) or have a setting just for flying things.
I would say the problem lies in when they choose to attack you. If from a design standpoint it's the right time for them to attempt attacking you, then it doesn't do much good if they're too slow to pull it off. An aggravated enemy that has no actual effect on the player is wasting CPU cycles. I know that's exactly what I did by modding them to be slower, but that was only for lack of a better solution using the xml hooks available.
The ideal design in my view is to make this attack-if-on-vehicle behavior conditional so it
only applies on horde night. There can be other situations that trigger vultures to attack, like if your health is low or the sleeper volume told them to. But the 'player is on vehicle' trigger shouldn't apply by default.
Vultures don't hate vehicles. There's no reason for them to 'see red' just because you're on a vehicle... except on horde night, where it's implemented as a necessary evil to correct an imbalance. Even on horde night, there's probably a more sensible way to address the imbalance of fleeing the Blood Moon horde with a vehicle.
You know, it's funny. Long ago I raised the hypothetical of zombie ghosts: entities that could fly straight to the player, at unlimited speed, right through any block. My purpose was to illustrate that the devs could always 'win' against whatever tactic players come up with, if they really wanted to. Except for the going through blocks part, that's exactly what they did with vultures. But it comes back to what behavior they're trying to discourage as 'wrong'. I see the case for hampering the player from avoiding the Blood Moon horde they elected to have turned on. Hampering the player from using vehicles in the desert, not so much.