Thats Cute, run one of the solids red or green then add the flags, hem with the other primary. He'll love it !!

My two grandsons would LOVE that quilt - the brighter the better!

it is great the way you are doing it! and kids LOVE, LOVE, LOVE bright colors, lots of texture...keep going and finish it up! no reason to 'fix' what isn't broken.

Maybe alternate the primary colours with a black and white square like a starter flag, and use the left blocks in the border. I love the colours tho, and maybe you should ask him if he likes it!

If it really bothers you.......then you could throw bleack over it.....Now that is my shock suggestion of the day. Wakes you up doesn't it.
I might consider putting bias tape over the seams to frame the blocks. Ot some other decorative binding. This is just an initial gut feeling. It might soften the seam lines a bit. I would consider a single fold bias tape , a rick rack or other decorative tape.

I would add a narrow gold boarder and then the flags a somber binding will give the eye a rest. A great quilt for a child but then I'm partial to brights.

I would use some soft colors in the Blues, Yellows, and Pale Reds for borders. Maybe one of each--2" wide each. Then a binding of again one of the colors in the quilt, but again the darker shade--dark Blue.
I think that will tone it down some, but yet, I think people will expect bright colors with a car quilt.
I personally think it is great!
We get too hard on ourselves when we look at our own work, is my opinion. I finally learned to put it away for awhile when I get to where I am sure it isn't what I wanted. (Also before I might be tempted to cut it into little tiny pieces!!!)
Mariah.

I don't think it's too bright for a little boys quilt. I've found that when I don't "love" a quilt that I've got almost finished, usually putting a border on it fixes it.....I don't know if it just ties it together, calms it, whatever - it's usually what it takes to get me back to loving it.

I like it just the way it is. It is for a young boy, I'm sure he will love it.

I love colors, and what you have chosen is really nice.
I would leave it as it is, however if you wanted to tone it down I would take out the dark blue with the checkerboards in it, and use maybe the lighter blue as in place of the darker blue.
However, it does look great the way it is, your son will love it. Why not even ask him how he likes it, unless it is a surprise