I have the second one, it is quite sturdy and robust. If legal to carry where you are, it would be a bat and light in one.
I love the US of A…a guy starts a threat seeking a bright light & walks away getting a long barrel .45! 
Bottom line, if you want to be save, you need a better weapon than the enemy.
In the 1970’s cops were complaining that they are at a disadvantage because they carry revolvers while the “bad guys” carried semi-auto’s.
Yeah ditch the AAA strobe light with funky UI that will send you all over the place…get an AR or the civilian version of the MP-5, step forth & fear no evil.
For non lethal protection I would suggest pepper spray. Bear size can is best.
6-cell Maglight used to be quite effective.
If you're already concerned about being hijacked while sleeping then my guess is that sleeping in your car isn't a wise move .
As far as what to buy and why ...go with the basics . High cri a decent amount of throw /18650 rechargeable via usb port etc . A good flashlight will probably deter more than save your life . Rats generally scatter when the lights come on. If someone seeks to wake then rob you ..you already have real problems since it takes a special kind of crazy to engage an unknown individual asleep or otherwise .Your odds of needing a weapon to protect yourself are about 600,000 to one . Simply parking in a better well lit location probably makes the chances of being attacked 20 times less likely . remember too that if you're robbed while sleeping in your car ...you probably have nothing to lose anyway . Get a nice flashlight so you can show them plainly that you have nothing they want and that you're as broke as they are ... Worse case scenario maybe gift them the light .
People concerned with self defense aren't the ones usually looking for a fight .Using a flashlight in strobe mode on a person who's already considering doing you bodily injury is like Texas Shooter said just going to give them justification in their own insane mind as to why you actually did deserve a good arse kicking . ..might as well rob you too since you were asking for it.
Self defense is best left to those who think they can easily take out the assailant. Arguing with him will always be less effective than knocking him out .Dancing around him /lighting candles /sacrificing chickens and invoking Voodoo curses won't be as effective as shooting him in the kneecap ...Blinding him momentarily with a flashlight could be effective if it's going to be followed up by 27,000 volts to the groin .
The OP went missing. As many times as this subject comes up I’m starting to smell a rat.
Or just wear The Suit Of Many Hooks, following the example of the Wily Porcupine.
The best way to not get yourself in a dangerous situation is to avoid it . Sleeping in a car is asking for trouble in these days that we live in.
I am not Texas Lumens, I have never meet the man. But I understand he is a much nicer, wiser and smarter person then myself. Not the first time on the confusion. For our non Texas, non USA members. Violent crime in the States is greatly inflated by a few large cities out of control. New York, Chicago, Detroit to name a few. Get out of those areas the people are much more civil. I’ve been in law enforcement for 27 years now. You would be surprised how many times while helping a broken down motorist someone slows down and offers something to drink. Given a sandwich some of my craziest homeless will sit down and tell you how life has been lately. Some are just really crazy and if harmful to themselves or others I drive them to the county hospital for care. When I see them later many apologize for their behavior and tell me how life is going now. What drives us drives most in the world; family, friends, faith, good food, flashlights. This thread is soo far off that I don’t mind digressing more. When eating in uniform an old beaten van stops, out gets four kids, mom and dad. Waiter/owner said my meal was paid for. Made me want to cry, I paid for their meal and left before they found out. They told me “thank you for your service and God bless you” as I left. We have a lot of foreigners, most are very conservative and religious. They tell me stories about where they came from and how much freedom they now have here. Many more stories most good, some not so. I get sent out to the problems so I tend to see more negative. Yes, I carry a gun every where. No, I’ve never shot anyone. Pepper spray is close to a liquid hammer and leaves an invisible UV dye on them for a few days.
Back to whats left of the topic. Use the right tools for the right job. Flashlight for light. Pepper spray for defense. Improvise if you must. Brain for knowing when and where.
Nobody’s mentioned the car.
(viewer discretion advised) Justifiable Force Caught on Dash Cam | Active Self Protection - YouTube
Have a flashlight, have pepper spray, have a stun gun if you wish, have a gun also. Don’t forget a knife as a very last resort.
Know how to use them all OR don’t take them with you.
HOPEFULLY… you will not need any of them… chances are you will not.
BUT, IF it comes down to it… It is much better to have it and not need it than to need it and NOT HAVE IT. 
there are flashlights with high voltage shocker bezels
but the light part is terrible, if the shocker was just as bad it would be hopeless.
“Police deployed stun guns, because pepper spray proved to be ineffective.” “Police deployed tasers, because stun guns proved to be ineffective.” “Police were forced to discharge their firearms, because tasers proved to be ineffective.”
We see such content printed in news stories regularly. There is one main variable. Is it a determined attack? If yes, sensory aversion stimuli are useless.
You need to have lights with you. If somebody is advancing and you suspect they’re going to do you harm, hitting them with a light may buy you a couple of seconds at best. Any and everybody’s natural reaction will be to put a hand up to block the light from the eyes but they will still be able to advance and see your body from the waist down. It’s no different than driving into a setting or rising Sun. You put the visor down or you put your hand up and you block the light and you keep driving.
“I’ll be driving cross country and plan to sleep in my car during the trip. If I were threaten by shady character in the dark of night, would a good flashlight’s turbo mode (or strobe mode) effective enough to disorient the attacker, affording me a little time to get away from the situation?”
If ya gotta sleep in yer car (and who hasn’t….
, at least sleep in the driver’s seat with yer windows rolled up, doors locked, butt most importantly have da keys already in the ignition.
So……if you’re already in the car stay put in the car. Hopefully soon doing 90 per.
Common sense tends to go a long ways in just about everything in Life.
Butt yeah, a sturdy heffty metallic flash IS a weapon if need be IF ya got nothin’ else. The blinding part cood (BIG unlikely cood) buy time butt rapidly and yet smoothly (smooth is fast) turning that ignition switch is MOST likely yer best move. Practice this scenario at least mentally before falling asleep so it comes to you even if he loudly busts out a window.
The accelerator is yer best friend here.
Remember you’re essentially cornered/trapped in that vehicle. 
He’s (or they) free to move all around you. It’ll be REAL tuff to “blind” him much less through reflective/diffusing windows. The only person yer gonna blind is yerself. Becuz of these immutable facts he has by FAR the greatest advantage over you.
Git movin’. 
PS. Pre-plan how you will park. Git dam aware of your immediate surroundings. Think like him and watt he’s looking for. Always try to leave a way to motor exit. Don’t park between cars for example. So watt this obviously means is carefully choose where you’ll park up first.
PSS. Don’t forget a long press on that horn if ya have any doubts on who’s approaching you, hear voices, wakes ya up strange noises, etc. (Then press twice for the next pulse horn mode……)
PSSS. Don’t ever roll down a window even for watt you think is just a “little bit” to better determine watts just now going on. Have no “cracks” in your quasi-armored vehicle as it were.
My acebeam L19 green saved me from tresspassers. I caught two people sneaking into my back yard at 1am and so I turboed them with 570k candela in the face and they ran away.
They likely would have reacted mostly the same way if it had been a keychain light or by singing “Happy Birthday To You” with your best Marilyn Monroe impersonation. Although the acebeam probably got them to run a little faster and a little further.
This sounds like a good plan but staying in a cheap hotel, being able to use a proper bathroom and shower is a bit more attractive.