For the first one, i agree with LoopyShane too, the car needs to turn the wheels, but not only when it is sliding, but also on that first turn too.(Check out Fast and Furious, for reference, either one will do i think, but maybe Tokyo drift is best?)
For the second one, fix the visible white lines that rung along the jacket’s sleeves. it looks like he was copy/pasted into that scene with them.(there is also one on his nose, and a few where dots on his eyebrows) I love how the shots, light up his face.
For the third, i am not sure those sparks look real, but i am not sure on that, it just feels like something about them looks weird…
The fourth… The flip doesn’t look realistic, i think the flips are a bit too fast—slow it down a notch. The way you did the flip, when the car is on the side it looks like it is about to be turned over, but it magically flips back into upright position. But then now that i look at it it seems like there could be a torque causing it to spin and correct its position…hmmm complex shot… Very good though in general. (are there headlights on the car or a white plane cover? cuz of the explosion we should see no headlights, maybe a bit of glass around the edges of the headlights, but otherwise we should see inside the headlight case)
The last one…If you are going for realism, LoopySHane is right, i don’t think that looks like real blood, but then, i never seen that much in real life so i cant say for sure that is not what it looks like. But I know this, it looks awesome as is, if this was a game of some sort. It immediately reminded me of Dragon Age Origins.
Dude, i gotta say, you are doing an awesome job, this looks so good. Amazing man, keep it up! And good luck!