When reading the introduction of the Gospel of Luke, it seems very clear that he isn't really claiming to be inspired by God or anything. Rather he is saying that he thinks himself to be more worthy of writing these accounts because he knows the story from the beginning (and probably also because he is educated and not some unlettered person).
Luke 1:1-4 (KJV)
1 Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us,
2 Even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the word;
3 It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus,
4 That thou mightest know the certainty of those things, wherein thou hast been instructed.
What really gets me is his statement:
It seemed good to me also
And another interesting point is that he mentions that many people have written Gospels (which we have only basically 4 now):
Forasmuch as many have taken in hand to set forth in order a declaration
So I am interested to know, on what basis do the Catholics say these accounts are inspired or the word of God? The author sure doesn't sound to come off as that to me, it seems more like a historical account, albeit one that is theologically based, and not something that sounds inspired.