The Bottom Line For the back seat passenger, be alert, be helpful to the driver and don't make sudden moves.

I've read all the great advice on pre trip checks and driving safety rules on the highway, so here's some on being in the back seat.

Being in the back isn't a free ride though, especially on the freeway. You have to be just as alert as the driver so you can react in sync and not cause more problems. 

Remember that the driver needs to have freedom of movement and as much clear vision of the highway as possible. If you're in the back and you're wrapped around them like a koala bear, how do you expect them to turn and check for traffic when they need to? If you have your arms waving in the breeze, you're blocking their vision of what's behind them.

Since the driver needs to have both hands occupied on a highway, I act as copilot.  We developed hand signals for  I love you, bathroom break soon, bathroom break now, stop, everything's ok, and beautiful sunset. He'll raise his hand just over his shoulder so I can see it and send me his need signal. 

I also carry gum to slide into his path of vision. I never jam anything in his face or make a sudden thrust in his vision path... it's always a tap on the shoulder and a slow slide down and off to one side until he can reach it safely.

When passing big trucks on the freeway we prefer to move to the outside of the lane (right track) and give those tires as much room as they need. Same when we're in the express lane... too often people in cars don't notice you and pull from the slow traffic lanes right out in front of motorcycles... so we give them all plenty of room.

Going around corners when riding in the back seat, especially on highways, can be a challenge. You want to move in closer to the driver's back a little more and relax enough to move with them. Don't fling your body to one side, you'll throw off the drivers balance. Keep your hands and arms in close and trust the drivers sense of balance to get through it. It may seem like you're tipping, but trust the driver or don't ride with them.
A good tip in curves and corners is to tilt your head in the directon of the turn.

Understand that anything you hold up or pull from your pocket will be sucked away instantly if you don't have a good hold on it!  I have had rings sucked right off my fingers when they were too loose, I have had a scrunchie sucked off my hair when I hadn't wrapped it tight enough... my husband has even had papers sucked right out of his unzipped pockets when going down the highway! So zip up and hold tight.

One last thing... bugs. Bugs on a city street hitting your face sting a bit, bugs slamming into your face at 70 miles per hour really hurt and make a disgusting mess to clean up at the next break. I have found that I can tuck my head in so I am just peeking out from behind his neck, that way I can see and be alert but not wind up with bug juice everywhere.
[Webmaster note: A fullface helmet will protect you from the bugs] 

Keep everything you'll need why on the highway easily accessible but zipped in, develop hand signals for when the traffic drowns out voices, be alert and ready and you should enjoy yourself on the highway.