You need to stop this conversation before it begins.
There is nothing wrong with telling your father about your decision to lease this vehicle. In fact, you should! It's always nice for parents to hear what you're up to in regard to medium/large decisions.
You do not want to justify your decision to him. There's nothing wrong with explaining why you made a decision, but you are under no obligation to do so because this decision does not affect your father.
More importantly, you've described your father as someone who takes great care in other peoples' decisions. This is a good reason for you to not justify it at all, because...
When you list justifications for a decision, you are opening up opportunities for an argument.
How to prevent the argument
Firstly, you need to start the conversation as if you are telling them your decision. Do not make it seem like you are explaining, justifying, or confessing.
Hey Dad, guess what? I leased a new car!
Or let's say your parents ask you what you've been into lately, you can say "I recently leased a car for my commute".
You've indicated that at this point your dad will be upset. Perhaps he will try to argue.
Do NOT engage!
Here's a few sample conversations you can use to shut down a brewing argument:
Dad: Why would you do that?
You: I wanted to.
Dad: So you think that makes it a good decision?
Your dad may insult you, be angry, complain, etc, but at this point, he has nothing to argue with.
Hopefully at this point, he leaves it alone and the subject changes. But let's say he presses on:
Dad: Well, how much is the lease?
You: I'd prefer not to talk about finances.
Dad: You are making a horrible financial decision.
You: Well I'm finished talk about it. [Insert something that changes the subject].
If he keeps pressing, just leave.
Remember, it takes 2 people to fight.
Unfortunately, you cannot control another person's emotional reactions. He may be angry, bad mood, etc, but at least you can avoid a fight.