Generally, your motor vehicles should be transferred to your trust. In Ohio this is accomplished by taking the title to the vehicle, and the abstract or certificate of trust to a title office of the BMV. You should also add the trust as an additional named insured on any insurance policy, which can be accomplished with the form available here.
You should first check with your attorney whether the specifics of your state law makes doing so disadvantageous for some reason. In some states, liability may attach to the owner of a vehicle, regardless whether the owner is the operator of the vehicle.
Be careful following the direction of anyone to keep your vehicles outside of your trust. It is true that a spouse has a limited right to transfer two vehicles outside of probate in the State of Ohio, but the privilege does not extend to others (such as your children). Moreover, it does not include all registered vehicles, and is a creature of state statute, subject to change.
Particularly in states like Ohio, where there is no special liability that the trust incurs in the event of an accident, beware those that advise that liability is a reason to keep incomplete the funding of your trust. If you are operating the vehicle, and you are liable, the assets in you revocable trust are available to satisfy the liability. Keeping the automobile out of the trust, therefore, does not protect you.
And the value of the vehicles is irrelevant. As you probably know if you have reviewed the probate pages, the cost of probate may be prohibitive even for small or limited assets. The best strategy is to avoid, to the extent possible, the risk of probate, and not leave your family with the nuisance of even a summary administration through the probate court.