What is good to use for a base coat for the body of a car?

What you need is a "primer".  A flat coat to help other paint to stick to it.  Not a gloss coat, the gloss coat will come last to give the glossy look of a new car, you could use Future.

Yann Solo wrote:

What you need is a "primer".  A flat coat to help other paint to stick to it.  Not a gloss coat, the gloss coat will come last to give the glossy look of a new car, you could use Future.

Ok, gotcha. I have a can of Floquil flat. I could use that?

I can walk you through with my enamel paint process, I never used acrylics.

• Wash kit with mild dish detergent, rinse well and dry.
• Wet sand body with #320 - #600 grit, rinse well.
• Do any necessary body work, i.e. - spot putty.
• Wet sand body with #400 - #800 grit, rinse well.
• Wipe down with Isopropyl Alcohol, let dry.
• Primer with a primer paint or flat paint - color depends on final color coat *.
• Let primer dry then wet sand with #400 - #800 grit.
• Wipe down with Isopropyl Alcohol, let dry.
• Spray 1st mist coat of final color, let dry.
• Wet sand if rough finish with #400 - #800 grit.
• Spray 2nd mist coat of final color, let dry.
• Wet sand if rough finish with #400 - #800 grit.
• Spray 1st wet color coat, let dry.
• If rough finish, wet sand with #800 - #1200 grit.
• Spray 2nd wet color coat, let dry (hopefully final coat).
• Mask off and paint any stripes or two tone effects, etc...
• If slightly rough or not as smooth as would like, I polish it after a month with Meguiar's Scratch X.
• Apply decals.
• Wax with Meguiar's Gold Class Clear Coat Paste Wax.

* NOTE: If the final color is going to be a light color, such as white, light blue, yellow, etc... I primer with flat white or "light" grey. If the final color is a translucent color, I'll primer with either gold or silver depending on how dark of a shade I want. If the final color is a dark opaque color, I'll use any primer on hand, even ruddy brown. Krylon works, Testors spray cans, I try to keep some of the cheaper Krylon primers on hand including flat white.

When I was younger I tried clear coating a few cars. I didn't really like how they came out, too glossy and the depth looked too deep even compared to the real clear coated 1:1 cars. So I found the wax that gives a really nice natural car show finish instead. 

My process might seem like a lot involved. It does undertake a months worth of the body being tied up in the shop. But I start on the body first and while it's sitting and drying, I work on the rest of the kit. I take my time, wire the engine compartment, run brake & fuel lines, detail the dash, make seat belts, whatever I feel like adding to the kit. All along working on a step on the body as it dries enough to work on the next part of the process.

Actually, I start a few bodies ahead of time and then set them aside for when I'm in the mood to build. So while I spray the one I'm working on, I might spray 5 more (yes different colors LOL). Pack them back in their boxes when dry. Next time do the same thing. That way I have a bunch of bodies pre-painted waiting to be polished, decaled and waxed when I get around to building them. My winter time builds mostly.

I got to finish that spray booth before next winter. 

*gulp*

Wow, your very dedicated!

I do have some flat black Krylon in the garage I've used for car related stuff before. I guess that could work as well.

Oh, I don't know if you could say I'm very dedicated.

There are times I can skip some steps because the finish came out smooth.
I apply some of what I had to do on 1:1 cars to my modeling.

Right now I've been using spray cans and spraying outside on nice days. Hopefully when I finish my spray booth and start using my recently aquired AB, the procedure will become less complicated... I hope.

The flat black Krylon should work if you are going to spray a really dark color coat.

I've actually skipped the primer step quite a few times when spraying a solid darker color (even orange). But I always wet sand and wipe with alchohol so I have a rough clean surface for the paint to adhere too.