A good example for all of those threads about how easy it is to defraud car rental companies with discount codes and how nobody checks ID's and the like.
When something goes wrong, they do.
It doesn't matter whether OP knew that he was committing a fraud. All that matters is that he did not know that he was eligible for the discount because he did not check the terms of the discount. If he had, he would have known that it was for IBM employees and that he was not an IBM employee.
So, to save a few dollars OP may wind up paying out of his own pocket for a new vehicle and, depending on whether the LIS policy is voided if there is fraud in any part of the transaction, he may pay for damage to the other vehicle and for any injuries to anybody else.
It is worth taking a look at what it costs to replace a bumper on a typical American vehicle and what a typical ER charges to set a broken wrist. Those two relatively minor matters are a good guage for those who look at risk.