Cruise control can for some people help steady the gas pedal or throttle control. Since some of us have a tendency to vary pressure on the gas pedal. However for the rest of us, you will find the cruise control over accelerates instead of attempting to maintain a smooth steady speed, it goes by mph, so climbing a hill it will try to maintain that set speed and then going down the hill it slows so much that it has to again overacceleate to get back up to the desired speed, there is also a safety factor since you are not responsible for sudden acceleration that will occur on a grade. Generally we are like herding cattle or other flocking animals and prefer to cruise along at the same space and pace as our neighbors. The best mileage can be achieved by maintaining a steady speed and 65mph is safe and productiv e for that.
Overheating and using the airconditioning, there is some truth to this helping the vehicle if it starts overheating, but you have to be careful anytime your gauge indicates abnormally high engine tempatures. If you see steam or smoke coming out your hood or behind in your mirrors, pull over quickly, to avoid serious and expensive engine damage. Now if you see the temp gauge gradually going up while your driving , and you don't have a place to stop safely, turning your ac off and turning your tempature of your heater on high you will help the engine cool a little bit by using the coolant in the heater core and turning the fan for interior on high to cool it off a little bit. Putting the vent control on defrost is not very helpful because it will engage the ac compressor which puts more load on the engine and cooling system, the floor vent will tend to burn feet in hot weather, so the center vents are the best and open the windows and let it blow out that way, if the weather is cool use the heat inside but in all cases watch the gauge it can help for a fair distance, but will usually end abruptly as the system finally runs out of coolant. If you pull into a station and want to refill read on.
Refilling a overheated automotive engine can be tricky and dangerous. If the gauge is not pegged full hot leave the engine running and start spraying cool water on the radiator and hood , if it steams excessively be careful it can be too hot and blow steam and overheated coolant into your face, causing respiratory problems and possible burns, so just shut the engine off and plan on letting it sit for awhile. Otherwise refilling a hot running engine is best on the engine and the quickest way. It allows the cold water to intermix with the hot coolant and blend to a medium tempature, putting cold water in a hot engine can actually crack the aluminum block or cylinder head. Some vehicles do not have a separate reservoir or radiator cap or both, a reservoir system is best and safest, Alternating spraying the front of the radiator (the front of the car body opening)) and the reservoir so its cool enough to touch uncap it and put a bit of water in there, and stop and wait, sometimes it will be so hot it will blow back into your face from there but the more you put in it will slowly cool everything down and fill the system.
Cooling fans on a car or truck sound similar to a portable home fan, so listen for them, they should be on and if they shut off after refilling and you don't see any fluid leaking out you have gotten lucky. Otherwise either your fans aren't working or you have a leak, don't forget to look at the exhaust pipes and see if water is coming out the tailpipe if it is you may have blown a head gasket or intake manifold seal, check your engine oil and if it is chocolate milky looking you need repairs right away, and should get a towhttp://www.cscpowertechnologies.net.