Can or could

[zoobinshid]

Hello everyone,
Would you please tell me why in the sentence below the guy uses could and not can? Is it about the formal and informal usage?

A:I`m going to look at new cars tomorrow .why don`t you come along, I am sure you COULD get a good deal.
B:No, thanks I have alot to do.

Thanks in advance,

[Temico]

"Can" is more definite than "could". e.g. I can get you a discount = "I am sure to get you a discount." I could get you a discount" = I may get you a discount".

[hancherng]

I think "could" is putting in this sentence because it was more polite instead of "can". It would not be wrong also if we changed it to "can"