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Discussion Starter · #1 ·
I am shopping for a vehicle and considering the 2022 Tucson Hybrid. Compared to the RAV4 Hybrid the Tucson has a much smaller motor. I am wondering how hard the Tucson motor is working at 70 mph. Can someone tell me what your RPMs are at that speed, or something similar? Thanks in advance.
 

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In theory... Top gear for Tucson Hybrid is 0.77:1 * final axle ratio of 3.32:1 gives an overall gear ratio of 2.56:1. Tire diameter is 29.2". I believe that the RPMs work out to be 70mph*2.56*336/29.2" = 2062 RPM. At least that is the formula from Gear Ratio Calculating - Tech Article - Chevy High Performance Magazine

Next time I am on the highway I will try to check it. If my numbers or math is bad, someone here will hopefully correct me.

I am not sure how the electric motor factors into this and if the RPMs can be different on a hybrid depending on what the electric motor is doing, but that I don't know.
 

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The Hyundai system uses the electric motor mainly to assist the gas engine, first at startup, acting as a substitute for a torque converter between the gas engine and the transmission. Even when the gas engine is running, the car is moved initially by the electric motor until it the car is going fast enough for a smooth transfer to the gas engine. In times of low torque demand, like slow acceleration or at certain highway conditions like long flats or slight downgrades, the car can run in electric mode until more torque is required or the battery level gets too low. At all times the gas engine rpm is dictated by the speed of the car and the selected transmission gear. Toyota and Honda use much more complicated systems with more powerful electric motors. Their systems try to force the cars to use electric motors, using the gas engine mainly to power the electric generator. With Honda, the gas motor pretty much only drives the wheels at highway speeds above 65 0r 70mph. It has a fixed ratio transmission, so the faster the electic motor goes, the faster the car goes. The electric motor is screaming at above 10,000 rpm at those speeds and when the gas engine kicks in to directly power the car it is also screaming at speeds approaching 4000 rpm or more. That is why highway mileage is actually lower than around town. The other indicator that these cars rely mainly on the electric motors is that there is no reverse gear. They simply run the electric motor in the opposite direction, something that Hyundai's traction motor never does.
Toyota's system is even more complex. it has a cvt, but it is gear driven with a complicated planetary gear system that can go into overdrive, while at most times the gas motor is trying to maintain a sweet spot of between 2000 and 2500 rpm. Honda and Toyota can achieve slightly better fuel economy, but for me the power has the feel of driving a boat with an outboard motor.
 

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Discussion Starter · #4 ·
In theory... Top gear for Tucson Hybrid is 0.77:1 * final axle ratio of 3.32:1 gives an overall gear ratio of 2.56:1. Tire diameter is 29.2". I believe that the RPMs work out to be 70mph*2.56*336/29.2" = 2062 RPM. At least that is the formula from Gear Ratio Calculating - Tech Article - Chevy High Performance Magazine

Next time I am on the highway I will try to check it. If my numbers or math is bad, someone here will hopefully correct me.

I am not sure how the electric motor factors into this and if the RPMs can be different on a hybrid depending on what the electric motor is doing, but that I don't know.

Your reply tells me I simply don't know anything about axle ratios. I will do some reading and see if I can understand them. Thank you very much. Also, see my reply to Mungo544 below. Last, your computation of 2062 is right in line with my gas powered 2013 2.5 liter Camry. Again, I need to understand axle ratios.
 

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I had my Limited HEV at 70 today and the RPM (in the right hand turn signal indicator) showed 2x1000 rpm. The indicator does show 1.9 or 2.1 at other speeds, but that is close enough to 2063 for my accounting.
 

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Discussion Starter · #6 ·
The Hyundai system uses the electric motor mainly to assist the gas engine, first at startup, acting as a substitute for a torque converter between the gas engine and the transmission. Even when the gas engine is running, the car is moved initially by the electric motor until it the car is going fast enough for a smooth transfer to the gas engine. In times of low torque demand, like slow acceleration or at certain highway conditions like long flats or slight downgrades, the car can run in electric mode until more torque is required or the battery level gets too low. At all times the gas engine rpm is dictated by the speed of the car and the selected transmission gear. Toyota and Honda use much more complicated systems with more powerful electric motors. Their systems try to force the cars to use electric motors, using the gas engine mainly to power the electric generator. With Honda, the gas motor pretty much only drives the wheels at highway speeds above 65 0r 70mph. It has a fixed ratio transmission, so the faster the electic motor goes, the faster the car goes. The electric motor is screaming at above 10,000 rpm at those speeds and when the gas engine kicks in to directly power the car it is also screaming at speeds approaching 4000 rpm or more. That is why highway mileage is actually lower than around town. The other indicator that these cars rely mainly on the electric motors is that there is no reverse gear. They simply run the electric motor in the opposite direction, something that Hyundai's traction motor never does.
Toyota's system is even more complex. it has a cvt, but it is gear driven with a complicated planetary gear system that can go into overdrive, while at most times the gas motor is trying to maintain a sweet spot of between 2000 and 2500 rpm. Honda and Toyota can achieve slightly better fuel economy, but for me the power has the feel of driving a boat with an outboard motor.
Thank you for your reply. Your description of how the Hyundai hybrid system works is how I thought they all work. Hearing the differences between Hyundai and Toyota/Honda is a big surprise to me. I am a long time Toyota owner, but this gives me pause. As for Honda, I was having a hard time with the CVT. I really appreciate the info you provided.
 
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