I don't know what to do

[azz]

Can one say
a. This is the car I don't know what to do with. I can't keep it, and nobody wants to buy it.
?

Many thanks.

 

[andrewg927]

I don't know what to do with this car. I know "what to do" is fine in conversation.

 

[emsr2d2]

If you're pointing at the car while you speak and you are trying to make it clear to the listener that it is this car, not any other car nearby, you can use "This is the car I don't know what to do with".

 

[Tdol]

Can one say

One can, but there are a number of contexts where this would be less natural than I don't know what to do with this car.

 

[GoesStation]

I'd say that applies to nearly any imaginable context.

 

[Phaedrus]

Can one say
a. This is the car I don't know what to do with.

I don't like it. Do those who do like this one too?

a1. This is the car I don't know what I'm going to do with.

 

[Tdol]

I can't say that I like either of them.

 

[GoesStation]

The only way I can see someone using that phrase is if they were referring to a previous conversation: This is what I was telling you about - the car I don't know what I'm going to do with.