Can the dá structure be used like this, to point to the car and the purpose of the trip? Using á would make it “given to me at its driving home” which doesn’t make sense if I analyze it too deeply… the master plan behind asking this, is whether or not dá and á are totally interchangeable, and carry the same meaning regardless of context.

A F.F., I am curious about this too. And thank you for your discussion with Lughaidh as reading it has helped me understand a bit more about this kind of sentence structure. 🙂

From what I managed to grab, the do and ag formations and á don’t significantly differ in their meaning these days.

Lughaidh explained a better way to point out a purpose with le or lena

Tugadh dom buidéal uisce beatha le hól… (not “dá ól”) – there’s just le + VN, no relative possessive pronoun. The bottle (or whiskey) was simply given to me for drinking.
Compare to this:
Tugadh an charr seo dom le tiomáint abhaile… again, this is a wee bit ambiguos about whether I’m going home, or the car – it was just given to me for driving home.

Tugadh dom buidéal (1) uisce beatha le hól, agus cloch lena bhriseadh.
Tugadh dom dhá bhuidéal (2) uisce beatha le hól, agus cloch lena mbriseadh
Bottles of whiskey were given to me for drinking, and a stone for breaking them (relative).
Again, compare to the sentence about the car…
Tugadh an charr seo dom lena thiomáint abhaile, agus airgead le breosla a cheannach.
The car was given to me “for driving it” home, and I also got money to buy fuel.