Here are my translations:

RIDING IN A VEHICLE OR ON A HORSE, ETC.
куда ты ехал (кодга ты НЛО увидел)? Where were you going at the time when you spotted the UFO?
куда ты поехал? Where are you headed?
откуда ты приехал сюда. From where did you arrive here?
куда ты уехал? Where did you go?
куда ты ездил? Where all have you gone in your travels?
куда ты ездил в отпуск ? Where did you go on your vacation?
куда ты ездишь каждый год? Where do you go to every year?
куда ты едешь сейчас? Where are you going right now?


GOING ON FOOT
куда ты шёл (кодга ты нашёл мой кошелёк)? Where were you going at the time when you found my wallet?
куда ты пошёл? Where do you intend to go?
куда ты ушёл? Where did you go?
куда ты ходил? What sort of places have you been to?
куда ты ходил вчера? Where did you go yesterday?
куда ты ходишь каждый день? Where do you go every day?
куда ты идёшь сейчас? Where are you going right now?

Note that when you use the non-prefixed "unidirectional/determinate" past-tense forms шёл and ехал, it implies that something else happened en route -- e.g., while you were driving your car somewhere, you saw a flying saucer.

When you use the non-prefixed "multidirectional/indeterminate" past-tense forms ходил and ездил, it implies a round trip (i.e., the person has gone and returned) or several trips.

But in the present tense, the non-prefixed "unidirectional" forms like я иду or я еду don't necessarily imply that another action occurs at the same time -- only that there is a definite destination. я еду на велосипеде в парк is "I am riding my bicycle to the park," for example.

This is in contrast to the present-tense of the non-prefixed "multidirectional" forms я хожу and я езжу, which imply "I often/regularly go..." (Or, in some contexts, they refer to ability: я езжу на велосипеде can mean "I know how to ride a bicycle")