Reader Question I drive a 2006 KIA Magentis (6cyl)
Using cruise control when set at 50 the tach reads 1800
at 60 the tach reads 1500
at 70 the tach reads 1500
SO, do I burn the same amount of gas at 60 and 70 or do I go further
at 70 and burn the same amount of gas if I only went 60 ??
I use cruise in the city too. When set at 57 I get 1200 to 1500 RPM
on the tach depending on the incline of the road. Level is normally
1500, down slight grade 1200.
Hi there Vic,
I am not familiar with that model vehicle here in the states, but the principle is the same as any other vehicle. The faster the engine is turning over (RPM = Revolutions Per Minute) the more fuel it will consume.
Its like a ten speed bicycle, when you are in 1st gear you have to pedal real fast to get anywhere…keep it up for a while and you will soon run out of energy.
If you get the bicycle moving in 1st gear then slowly increase your speed and up-shift into a higher gear, you can go faster and use less effort. Once you get to the desired speed in a high gear it takes just a little effort to maintain that speed.
So at 50, you are probably not in the highest gear yet, but at 60 the transmission has shifted to high gear and the engine is now working less…but you are going faster.
I would assume you are consuming MORE fuel at 70 than at 60….to travel that much faster the engine would certainly have to be turning over more than at 60 unless there is another gear that was shifted between 60 and 70 causing the engine to work less.
At 60 MPH the transmission should already be in the highest gear selection, if this is 60KM, there COULD be another gear before 70.
The best rule of thumb is, the higher the RPM the more fuel the engine will consume. Cruise control is meant for highway cruising only…I would not recommend you use cruise at speeds less than highway speeds, and never in a city environment.
Safety is the number one reason for not using it in city driving, but you will not gain a significant amount of fuel mileage either…and you might actually decrease mileage.
Best ways to increase fuel economy are:
1. Keep tires properly inflated
2. Change air filter often
3. Use the proper weight engine oil, thinner weight oil is more fuel efficient.
4. Keep up with tune ups, spark plugs, fuel filters and spark plug wires
5. Buy a Toyota Prius 🙂