why does my car run hot - on the highway - but runs nice and cool around the city -?

Most often if it runs hot on the road its a water circulation problem..ie.. partially stuck thermostat, old radiator hose that collapse at speed... change the thermostat and the lower radiator hose...good luck

that's kind of weird, but it could be that your thermostat is sticking and working properly, if its overheating while your idling than most likely its the clutch fan............... Also check your radiator fluid after the engine is cool never check when hot. keep your fluid level always at full hot b/c... when driving on the highway usually means longer distance which means the engine gets hotter and the radiator starts working more so first check your levels if it does not work try a new thermostat they're like 6 $ least in VA.

On the highway, the V8 needs more power which makes more heat and and there isn't enough air cooling the radiator.

When driving in the city, you are not going as fast and always stopping for lights, so its not as hot

It doesn't matter though, as long as it doesn't overheat

first check for trash (plastic bags, etc.) in front of radiator/condenser. If you have no coolant leaks and hoses are in good shape check the radiator for stoppages, usually it's a rusty mud that plugs the inside from the bottom up. Sometimes the condition of the coolant can alert you to potential problems, is it nice and green or reddish-brown and rusty. Thermostat would be a good idea regardless.

Usually because in the city you sit idle more often and the air doesnt go through the radiator and fan as much as free open range on the highway!

on the voyager it has an electric powered fan so i could say your water pump belt is unfastened or your water pump is failing no longer unavoidably leaking despite if it has a great variety of buildup in it and whilst at idle it may do the interest yet at larger speeds the cooling is dwindled. you need to look right into a flush whilst your below the hood.

missing airdam trim peice below the radiator to force cool air through at highway speeds?

Perhaps your thermostat is stuck, that happened to me several years ago which caused it to overheat on the highway.

Check your fan clutch to insure it works. Also check your transmission to insure it is going into high gear so that your engine doesn't have to run fast.

Your car is too old to drive constantly 55~65 mph....it gets overheat, ...