In most cases, this is not a fatal error by the police.
Your 'Miranda' rights are only necessary once you are in custody and only if the police are asking you questions. This is known as custodial interrogation. These two parts of the equation are crucial to determining if your Constitutional rights have been violated.
In most cases of simple traffic stops, you are not 'in custody' for the purposes of Miranda. Once you have been arrested, you are certainly in custody. There are situations where a court would find that you were 'in custody' prior to being restrained in handcuffs and then placed in a patrol car. These situations are extremely fact specific.
In this context, Miranda only applies to questioning by the police. If you blurt out "I'm not going to do that test because I am too drunk," or "I'm so wasted," those statements are not protected by a failure to provide a 'Miranda' warning because they were not made in response to police questioning.