Automobile ads kept magazines going through good times and hard. High-ticket items, they could afford to pay for color reproduction when that was too expensive for most other products. Everybody knows something about cars! Some of these ads were created by the best artists in the business. And some of them are just fun to look at as nostalgia; or, if you prefer, ancient history. Trucks here, too. Also wagons and carriages.
If you like these, check out this great website of scans of illustrated automobile sales brochures