I have a question

Well, for a starter, make sure that you are alone and that there are no kids or minors around to witness your activities.

You can find a secluded place in a public part for example and go braless. If you have the opportunity, take a cooler and place, besides drinks that you will need to cool off, also ice cubes. They come in handy for the show.

When nobody looks, simply rub your nipples with an ice cube and see them react to the cold. Lift your top to show your BF the reaction and see his own reaction...

Wear a button front dress with no underwear. Undo the buttons as he drives. I’m sure you can take it from there 😁

Wear revealing tops (no bra) and micro mini skirts.
Suck him off while he's driving.

Have sex on a picnic table

Drive naked

Lie across his lap with visible midriff &/or buttcrack.

Show your tits in an adult theater and post the pic.

There is one way to do it correctly and that is to make it look like an accident and if it is your kink hold eye contact for a moment with the person who got to see the show.

* I assume this is not for your BF's benefit he gets to see it all anyway.

No panties or bra. Hike up your skirt, finger your pussy while he drives.
Let him finger you in public

go up in a multi surface carpark at night