Many car dealers offer promotional 0% interest rates on financing for x years after the purchase. I know this for absolute fact. I'm really astonished (and a little bit disturbed) that you aren't aware of this.

I know I don't "need" it and if you'll read my post again, I didn't say I did. I already have credit that would be fine for buying a house with, but my credit reports mention lack of installment loans as one of two or three items that still negatively impact my score to a minor extent. If it helps you focus more clearly on the question, just disregard the house part and think of this as me just wanting to get my credit as high as possible because it makes me feel good inside.