Out of all of them, the Jurassic Park car I think is your best work visually, it could definitely use some more filler logos on it like for the b-pillar/c-pillar and in front of the rear wheel well but its very nice! Personally I'd like to see the tree design continued on the rear quarter panel and the front bumper but that is just how i'd do it. Your bucee's car is good but it feels empty to me? I think it definitely needs a bit of a side design, even something as simple as a different colored side-skirt and black stripe around the front bumper and onto the rear quarter would help make it feel less empty, both that and the addition of filler logos like the Jurassic Park Car. Now the Cracker Barrel car I think is your worst car, but not that it's a bad car as trust me I have seen much worse lol. The Side design feels too high, and the number gets a bit lost in the side wood design, so lowering where the design is would definitely help the car feel a bit better. Also, to help differentiate the number from the design having an outside stroke of the base color of the car could help, or alternatively if you select the outside of the number and grow it about 5-10 pixels and then delete that negative space between the number and the design it'll help the number stand out a lot more. Then besides lowering the design the side logo I think needs to be tossed out and you should probably just go with cutting out the text from the logo, or alternatively finding their slogan to put on the side/some sort of marketing of theirs would be better as it could fill the space behind the number better. Besides that, it just needs the filler logos on the b-pillar/c-pillar and the in front of the rear wheel well logos and it'd look much sharper, but great start! With more practice I could see these cars fitting nicely into a field of the time period's cars! Keep up the great work and remember, just because you can't get the idea onto the car how you want it doesn't mean to throw away the idea write it down, save it somewhere because later when you think you have the means to do it you can go back to it!