"I remember once sharing the Gospel with a businessman. When I explained that Christ had died to pay the penalty for our sins, he responded, "Oh, yes, that's imputation." I was stunned, as I never expected this theological concept to be familiar to this non-Christian businessman. When I asked him how he came to be familiar with this idea, he replied, "Oh, we use imputation all the time in the insurance business." He explained to me that certain sorts of insurance policy are written so that, for example, if someone else drives my car and gets in an accident, the responsibility is imputed to me rather than to the driver. Even though the driver behaved recklessly, I am the one held liable; it is just as if I had done it. Now this is parallel to substitutionary atonement. Normally I would be liable for the misdeeds I have done. But through my faith in Christ, I am, as it were, covered by his divine insurance policy, whereby he assumes the liability for my actions. My sin is imputed to him, and he pays its penalty. The demands of justice are fulfilled, just as they are in mundane affairs in which someone pays the penalty for something imputed to him. This is as literal a transaction as those that transpire regularly in the insurance industry." - W. L. Craig, "Question 122, Subject: Penal Theory of the Atonement."
Craig is right to say that the owner of a car can be held vicariously liable for any negligence committed by someone to whom they have loaned their car. But what he omits to mention is that the driver must be using the car primarily for the purpose of performing a task for the owner.
For this kind of imputation to work as a parallel to substitutionary atonement, then, it would have to be the case that when we commit sins, we are acting primarily so as to achieve the purposes of Jesus Christ! Only then could he rightly be held liable for our sinful actions.
Don't think that one is going to work too well!
This kind of 'test' is also used when imputing liability to a corporation for the acts of its employees. A corporation can be held vicariously liable for the acts of its employees only if (1) the employee acted within the scope of their employment; (2) their actions, at least partly, benefited the corporation; and (3) it would be reasonable to impute the employee's acts and intentions to the corporation.
None of these three conditions find a parallel in the doctrine of penal substitution. Quite the opposite in fact.
(1) When we sin, we are acting against what it is that God has demanded of us. (2) It is hard to see how our sinfulness could, even partly, be said to 'benefit' Jesus Christ. (3) It could never be reasonable to impute our sinful acts or our sinful intentions to Christ himself, since he is, by definition, incapable of sin.