Is it permissible to purchase a car through a bank with a 4% interest rate, knowing that canceling the commercial order necessitates paying a sixth of the car's price, and I do not possess the amount?

It is not permissible to take out usurious loans except in cases of dire necessity. Paying a penalty for canceling a commercial order is not a necessity that permits this, and the company is not allowed to impose any penalty on you. However, if having this amount taken from you would have a significant and severe impact on you, then it is permissible for you to continue with the contract due to necessity, which is the preservation of wealth, while trying to reduce the usurious interest through legitimate means. Similarly, coercion is permissible if a lawsuit filed against you would lead to your imprisonment and harm.