How do modern cars regulate temperature so well?

408, aluminum heads, solid roller cam, stock pulley ratios, dual electric fans, aluminum radiator, 180 thermostat, AC, sequential port EFI. It will maintain 180 when cruising but climbs to about 195 when in traffic, but drop right back down once I get moving. FYI. I live in south Louisiana. I just had it out over the weekend. It was 95 degrees out and I didn't have any problems. Contrary to what another comment was about sequential not being worth the trouble, while the difference may be minuscule, the car does idle better with sequential EFI. It wasn't designed for high RPM as he stated. It was designed originally for low RPM emissions.
Do you have stock ratio pulleys? Do you have a 6 blade or 8 blade water pump? I'm not a fan of the aftermarket pulleys since they slow down the water pump so much. They may work in the northern states, but not down here.