Upgradable truck

There is an upgrade to dump truck and liquid truck that come with a capacity increase, could we get an upgrade to the truck capacity? or the ability to build more of them? A lot more of them. Even if it cant switch between vehicle types like the regular truck. My busyness icon doesn't leave red/very busy in the later game. Bigger and more trucks would be very helpful

already in the game research better trucks or use unity in the office to slightly increase the capacity