I had this idea for a jumper for my son long ago and it took me a long time to turn that idea into an actual design. Seeing it come to life involved a lot of frogging and mistakes but I finally got there and I am so pleased with it. It comes in sizes newborn to 2 years and is generous in sizing. It is made using stocking stitch with blocks of colour. You make the road markings by stitching on afterwards using duplicate stitch. The cars are then knitted separately and sewn on however you want them making each version unique.

I used Stylecraft Special DK but you could use any dk weight yarn provided you get the same tension. Use any scraps of yarn you have for the cars, they take less than 10g of DK each.

Materials
Stylecraft Special DK 100g balls or any other dk to get same tension (295 metres per 100g)
1 ball in main colour, 1 ball in contrast colour
The jumper pictured has stripey sleeves. Should you wish to have sleeves without stripes you will need 2 balls of main colour for 2 largest sizes.
Oddments of White (road markings and car windows), Grey (wheels), Blue (car body), Red (car body) and Yellow (car body) yarn - approx 10g or less of each - for applique
2 buttons
Pair of needles 4mm (UK 8, USA 6) and 3.25mm (UK 10, USA 3)
Tapestry needle
Stitch marker
Stitch holders