Should Jackson be in his crate while driving? Or no crate at all?

For Jackson's well being, I'd have him travel in his carrier or secured somehow. One reason is to keep him from getting under your feet as you drive. And it also keeps you safe.

I would absolutely not let a cat loose in my car while driving. Even the sweetest natured cat can get spooked, and you DO NOT want this to happen in traffic. My Fred, now gone to the Bridge was the sweetest kitty ever, and I had been his mommy since he was a few weeks old. We were driving through Nashville during rush hour, and he got out of his carrier. He attacked me, clawed at my face, ran several laps around my neck, bit me several times all in the matter of a few seconds. I finally managed to stuff him back into his carrier, but for a split second I wondered if I might have to open the window and let him go before I had a horrible wreck involving more thatn just me. I looked like I had lost a fight with a cheese grater. I should mention that it had been a ride from NC, and he had been given meds, but it could still happen even without them.
Several years ago there was a horrible wreck here that was caused by a kitten getting under the brake pedal. 4 or 5 people and 3 kittens died whe the person driving went off a curve and hit an oak tree because she could not get the brake pedal down in time.
Unless you have a way to completely isolate from you while you are driving, having him get used to his carrier would be the safest thing, INMHO.
I am not trying to scare you or sound mean or bossy, I just want you, Jackson, and other people on the road to be safe.

You decide after this true story.

A friend was taking their cat to the vet one afternoon. The cat was sitting in her lap (she had another driving). Cat always was loose in the car - nothing ever happened before.

Out of nowhere a fire engine came thru the intersection (they were sitting at the red light). The siren was blaring; the cat panicked and leaped forward to get away....right into the front windshield! Crack his skull and was bleeding.....was dead before they got to the vet.

Now do you still want your precious kitty to be loose in the car?

Absolutely in the carrier.

I let Dori sit on the seat once. She was so upset in her carrier that I opened the door and let her out. She was so scared she jumped down off the seat and tried to hide by my feet, right in the way of the brake pedal. Luckily I was driving a stick, so I managed so slow down enough and ran up a curb to stop myself so I wouldn't squish her with the pedal.

My vet told me a story about a woman who had her cat loose in the car and had a car accident right outside of their office (they are on a busy road). The cat ended up escaping from the car, darted out in traffic, was hit and killed.

I kinda give Oliver limited freedom in the car... it's a 4 hour car ride between home and school for me and Oliver frequently makes the trip with me (If I'll be gone longer than a week, it's not fair for him - he's FIV+ and her cats aren't so he has to be confined to one room while he's there... when she can, she'll confine her two cats for awhile and let Oliver roam).... Oliver has a soft sided carrier which has a leash hook... he always gets "suited" in his harness and leash and the leash attached to the leash hook... then the carrier is secured to a seat in the car... after we get onto the highway I stop to open the top of his carrier... if I do not and leave him inside, he literally turns into a devil spawn: hissing, screaming, spitting... it looks like those cat fight's you'd see in cartoons - and he WILL do that for the ENTIRE 4 hour trip.... needless to say, that is not healthy for him. So with my set up, he can walk around a little bit and have access to his litter box on the floor of the car - he'll pant and cry a little, but that's much less stressful than what he does if left in the carrier... I know being inside the carrier is usually the safest thing, but I'm scared that his actions inside the carrier for that long could give him a heart attack or something... he will only act this way on long trips. If we're just hitting the vet or the kitty sitter's across town, he's fine inside the carrier - I think he knows by all the luggage and such that we're in for a long haul....

PS: I have tried giving him different things that are supposed to calm him down and the only effect they've ever had on him was making him puke (even when I pull up his food and water the night before)....

I too crate ... there are some really kewl cariers out there if yoou dont mind $$

When we first got Trout, I was taking her to the vet for the first time and I didn't have a carrier yet..She was standing up on the back of the front seat..and I had to brake hard and she went flying against the back seat!!

She just shook it off, but she could have been really hurt.

Ever since then, I've always used a carrier...(also the vet tech gave me a dirty look not having Trout in a carrier)