Purchasing new cars

I have two questions.
Say if you want a Toyota and your fiancé wants a Toyota and you decide to buy them together...do they give you some sort of incentive or discount for purchasing two cars?
Also, if you have enough money to buy a new car outright, is it better to do that option or to pay for at least half and then make payments on the rest?
It's obviously our first time buying new cars and we plan to spend about $85,000 together. The 2 cars we want are both $42,000 or in that range. 
Everyone gives us different answers. They're saying that we will get screwed at the end of the year with taxes if we buy them out right. Can anyone give me any tips.