I agree that this was probably inadequate training as opposed to a deliberate deception. That being said, I think a letter to Budget explaining what happened would be in order.

Most rental companies take great pains to point out that the car you reserve may be substituted by something "similar". "Similar" typically means something with the same number of wheels as the one you reserved, if you follow me.

However, if an agent at the counter promises that your vehicle has a particular feature, it had better have that feature. It's not the customer's responsibility to know whether a Chrysler Pacifica has 4WD or not, or even what the heck it is in the first place. Granted, if you get out to your car and it's not what was promised, you should go back in right away. However, that's not always practical.

Budget probably doesn't "owe" you in the legal sense of the word, but a good gesture on their part would be a partial refund or a voucher towards a future rental day.