If I wanted to have a scene with my characters in a car, would I have it be

EXT. Jaguar - Day

or is there a better way to format it.

All help is appreciated.

If the scene takes place inside the car, INT.

If the scene is outside the car, but the people are inside, EXT. Like if a cop car is chasing your characters' car.

If the scene is both, like the characters getting in or out of the car, or they have been stopped by a cop and the cop is outside and they are inside, INT./EXT.

Depends on whether or not the car is moving. If it is, write it like this...

INT. CAR - TRAVELING - DAY



If the car is stationary, simply do it like...

INT. CAR - DAY

I second everything said up to this point, but I do want to clarify one point. If this is an EXT scene, the location isn’t the car, it’s the place where the car is driving.

EXT. DESERT HIGHWAY - DAY

A yellow Camaro speeds down a lonely stretch of sun-baked road. Drunk and disorderly BILL (21) leans out the passenger window and yells incoherently.

INT. CAMARO - TRAVELING - DAY

Equally drunk driver KATE (20) looks at Bill’s rear rather than the road.

There's nothing wrong with the example you provided. There are numerous variants you could try, but when in doubt, keeping it simple is the way to go. EXT. JAGUAR - DAY is fine. The only alteration I'd suggest is if it takes place in a moving vehicle, in which case it would be EXT. JAGUAR - DAY (MOVING).

I get what FrankM is saying about the car not being the location, that it should be where the car is driving. But I'd argue that if your intention is for the viewer to be observing the occupants from just outside the window (which is a very common angle you see all the time in movies) and you have no intention of cutting away to anything happening outside of the car or in the surrounding area, then the car is indeed the location. But there is no rule on that particularity.

Just aim for clarity above all. If you're confused on how to write something, the reader will be confused when they read it.