Thanks for adding the title and genre, as this affects editing comments.
Last tank of gas, Kumari thought as the engine spit out a black cloud before picking up speed. It meant one thing: last chance to make a catch. Last chance to eat, drink. Last chance to stay alive
"Harder!” Kumari screamed over the howl of the battered engine.
break here because we have a different person talking that acting.
Bastion punched the gas pedal, dust and pebbles spraying the old army Jeep in a peppered (PEPPERED IS STRONGER VERB THAN SPRAYED, SO DON'T USE 2, JUST ONE -- IT WILL MAKE THE SENTENCE LESS AWKWARD) graffiti. Bits of dirt clawed her (BASTION OR KUMARI? THIS USED TO BE THE SAME PARAGRAPH, SO I'M NOT SURE) cheeks and scratched (STRONG ENOUGH VERB AFTER 'CLAWED' HER FACE? MAYBE PELTING?) the surface of her shades. She adjusted (VAGUE VERB -- I SUSPECT SHE COVERED HER FACE WITH THE BANDANA IN RESPONSE TO THE DEBRIS SPRAY) the bandana across the lower half (DON'T MATCH A VAGUE VERB WITH VAGUE DETAILS 'LOWER HALF OF FACE' -- SHE COVERED HER MOUTH AND NOSE TO BREATH IS MORE VISCERAL) of her face.
1) Visceral is good for this genre, so this gritty opening is heading the right direction. But note that most of the grit is related to the car and environment. Not the characters. Shades and bandana are good details, though. What else you got?
2) "It" is a weak word, and not one that should lead a sentence in an opening paragraph, especially here because you have the "last tank of gas" and the "black cloud" to which "it" can refer. So which is it?
3) We can't see Kumari and are left with more of a sense of the vehicle than her/him. That vehicle better be important enough you spent your opening on it. And it better reappear in the book. Only open with your key characters and devices that thread through the rest of the book.
4) "Picking up speed" is cliche, which is definitely to be avoided for your genre. Be "in character" when you comment on movements, inanimate- or character-related. How would a dystopian future call this? Consider creating a list of your world's sayings/idioms.
5) My biggest concern is the lack of feeling we have for either person introduced. They have to make some "catch, eat, drink, stay alive." We know their external goal. But personally, I don't give a wit for either person. I've no reason to. And this is a key issue in most openers. Give the reader someONE (not someTHING) to care about immediately.
6) A freind of mine writes sci/fi and some dystopic, and she's always sure to include something in that opening that tells you that you're in another world. This opening could be modern-day Vegas for all I know. Add at least one element of surprise.
Introducing heart from the first page, the first 'graph is very hard. But that's the challenge. Given the good writing here, I know the author is up to the task. Good luck!