For sizes 2 years to 6 years, this is what all little boys would want to wear! Maybe even girls too, but remember to change the buttonhole band to right side for girls, left side for boys.
This is made in a little lighter weight size 4 worsted weight yarn. We used Lion Brand Pound of Love, a 16 ounce ball of 1,020 yards. This jumbo ball of yarn will make 2 sweaters in smaller size.

You can add as many cars as you wish while knitting away. The smallest size has one car each side, the larger sizes have 2 cars each front side. Color graph is easy to follow and only a few short rows and you are done.