Below is my version of the pattern. I use a (FREE!) knitting app on my tablet called Visual Knitting Counter and every pattern I post will be compatible to copy-paste the text into it, in case you use it too or want to try it out.
Black or dark gray yarn
Orange or yellow yarn
2 to 4 car buttons
US Size 6 double-point needles
US Size 4 double-point needles
Optional stitch marker placed at start of new row to keep track of when knitting in the round.
12-month size Car Mittens:
Using green yarn: Cast on 25 sts on smaller 2-3 double-point needles.
Working in the round, *K1, P1* until cuff is 1 1/2-2" long.
Switching to larger needles: Switch to dk gray/black yarn, K 25. You may choose to alternate green and gray for this first row to add the illusion of the grass blades but you can't really tell (see photos).
Begin thumb increases at the start of the new row, by inc 1, K1, inc 1, K24.
Inc 1, K3, inc 1, K 24
Inc 1, K5, inc 1, K24
Inc 1, K7, inc 1, K 24
This is the row where you will start the road stripes. K1 gray, *K5 orange, K5 gray,* repeat until row is done.
Inc 1, K9, inc 1, K 24. Make sure to follow the color pattern you started in the previous row!
K35, following color pattern. This is your last row of road lines, so they are 3 rows wide.
Transfer 10 sts to 2 other double-point needles: These sets will become the thumb.
Knit in the round in your road color for 8 rows, so that there are an equal number of rows on either side of the lines in the road.
At the beginning of your next row, start your blue yarn. This is your sky, and you're almost done.
K 3 rows.
*K5, K2tog* 4 times, K3
*K4, K2tog* 3 times, K3
*K3, K2tog* 3 times, K3
*K2, K2tog* 4 times
*K2tog* 5 times (6 st remain)
Close the small hole off from inside the mitten.
K8 rows with your road color.
*K2tog* 5 times
Bind off, closing off the hole from inside the thumb.
Add buttons to the backs of both mittens, so that you can tell which is the back and the palm.
If you have never knit with multiple colors, you want to make sure you cross the color yarn you just stopped using over the color you are starting, like so:
I am stopping the gray and beginning the orange.
When you pull the gray tight it will not show on the outside of the mitten.
Since I do not recommend using individual lengths of thread for each new block of color the inside of your mitten will look something like this:
So you want to pull the yarn tight enough to not show through while still keeping it loose enough to stretch when worn. You might decide to practice this a little bit depending on how much stretch your yarn has.
Please let me know if you have a hard time with this, or if I am not explaining it easily enough for you to try.
Here is another close-up to motivate you to make these for the little boy(s) in your life.
The car buttons I found all face the same way, and the mittens looked a little odd with just one car on them, so I'm pretending they are on a one-way road. You might have a better or different outcome if you have a different button selection than I did.
Good luck and happy knitting!