Oh do fuck off Microwave. Tablet time isn't crack.
OP, my DS3 plays with his cars all day long. Cars in water, cars in sand, cars in playdough, with a toy garage, cars in paint, wrapping cars up in paper, hide and seek the cars in the garden etc etc. The Disney Cars branded ones are overwhelmingly more popular with him, even before he was interested in the movies. I think the faces and the quality of them appealed. If you have a car fan, I'd recommend splashing out on some of the Disney ones. B&M, Smyth's, Asda and the Disney shop tend to sell them. We've also had huge success with Hot Wheels colour change cars, he has spent hours and hours with them with bowls of warm and iced water.
He also spends a lot of time playing with play dough. We have a few sets, my 3 year old has the fire truck, I wasn't sure it would have much play value over regular cutters and rolling pins but is played with nearly every day. The popcorn and burger set have also been popular. I'm a total convert to the gimmicky sets now.
Other favourite toys here are wooden train track, Duplo train track (more popular than the wooden), and a Carrera scalextric thing. The Carrera track brings him so much joy, but is a pain in the sense to set up and needs adult supervision, so not ideal for getting things done while they are occupied. We have Way to Play rubber road too, which is mostly played with in the garden.
Orchard toys games and puzzles are always a hit too. A marble run, we have a wooden one and a Galt one. The Galt one is probably used more. Magnetic tiles, Mr Potato head is popular, but you need a bundle to get the most play value rather than just one potato. A doll, my son has a tiny treasures mini doll he is quite taken with.