I daily drive (4S PB+ 20") around 150 km with the trip computer showing an avg. speed of 95kmph (normal mode with AC on normal at 22C, in ambient temps of 37C-44C), i can confidently say that the car can get 290miles (465km) at 100% SoC
Can you share your consumption data - miles / kWh - available from 'Total Trip'?
Mixing metric and imperial units in calculations invites error, so being a not very trusting soul I felt compelled to do my own calculations from scratch...and must now applaud your accuracy.
Wow...incredible work. I feel stupid as I just want to drivetldr; 146 miles
I didn't double check any of this so there's a non-zero chance of errors, which I will correct if pointed out or if I find myself.
Some basics
If energy is 83.7 kWh (user-accessible battery capacity) and distance is equal to 300 miles, we can say that the car used 0.279 kWh per mile or 27.9 kWh per 100 miles.
Because work (energy use) is equal to force times distance, energy per distance is a unit of force. i.e. the 27.9 kWh/100mi tells us something about the force required to move the car (although not entirely because not all of the energy was used for force).
Note that one kWh/100mi is equal to about 223694 N, but I actually like kWh/100mi better for this exercise, so we'll keep it. And this is 17.3 kWh/100km going 482.8 km at 112.6 kph for the metric people playing along at home.
Drag is a drag...
The dominant change in force for a change in speed will be drag. The drag force is equal to the coefficient of friction times the area times the fluid density times the speed squared.
Porsche has published the drag coefficient as 0.22 Cd and the frontal area as 2.33 m^2.
Air density is 1.2 kg/m^3.
Other standard units are meters per second and, with an additional scalar of 0.5, the equation yields newtons. But we don't want N or m/s. We want kWh/100mi and mph.
So, we'll plug in the numbers for air and the Taycan, add some other scalars to convert units to our (my) preference, and we have the below:
Drag force in kWh/100mi for a given mph:
mph^2 * 0.00273
And the metric folk: kWh/100km for a given kph:
kph^2 * 0.00066
Okay, so now we can say, at 70mph, the drag force is 70*70*0.00273 or about 13.3kWh/100mi. (8.3kwh/100km).
So, of the 27.9kWh/100mi consumption rate, 13.3kWh/100mi is from drag.
This leaves 14.6kWh/100mi that we won't change as speed changes*.
(9.1 kW/100km)
Now, finally, for the OP's question, how does the range change at 125mph?
125*125*0.00273 = 42.7 kWH/100mi(26.7 kWh/100km)
This is the new drag force to replace the 13.3kWh/100mi at 70mph.
Add the 14.6 kWh/100mi and we're at 57.3 kWh/100mi. (35.8 kWh/100km)
Going back to battery energy of 83.7 kWh divided by 57.3, and times 100, we get....
146 miles (234 km)
----------------
*This 14.6kWh/100mi does likely change some with speed. For example, there are some time dependent energy uses such as AC that improve this number at higher speed. Rolling resistance may change some as tire temperature changes from the different speed. But as others have pointed out, the drag is by far the largest factor...and also most straightforward to just calculate.
Hmm. I just did 2 journeys of around 200 miles. Average 65mph and 55mph. Temperature around 12-15c. Mostly motorway.
Jason Fenske, Engineering Explained would give you an "A" for the homework assignment! I felt like I was listening to Jason as I read your post. Nice job!tldr; 146 miles
I didn't double check any of this so there's a non-zero chance of errors, which I will correct if pointed out or if I find myself.
Some basics
If energy is 83.7 kWh (user-accessible battery capacity) and distance is equal to 300 miles, we can say that the car used 0.279 kWh per mile or 27.9 kWh per 100 miles.
Because work (energy use) is equal to force times distance, energy per distance is a unit of force. i.e. the 27.9 kWh/100mi tells us something about the force required to move the car (although not entirely because not all of the energy was used for force).
Note that one kWh/100mi is equal to about 223694 N, but I actually like kWh/100mi better for this exercise, so we'll keep it. And this is 17.3 kWh/100km going 482.8 km at 112.6 kph for the metric people playing along at home.
Drag is a drag...
The dominant change in force for a change in speed will be drag. The drag force is equal to the coefficient of friction times the area times the fluid density times the speed squared.
Porsche has published the drag coefficient as 0.22 Cd and the frontal area as 2.33 m^2.
Air density is 1.2 kg/m^3.
Other standard units are meters per second and, with an additional scalar of 0.5, the equation yields newtons. But we don't want N or m/s. We want kWh/100mi and mph.
So, we'll plug in the numbers for air and the Taycan, add some other scalars to convert units to our (my) preference, and we have the below:
Drag force in kWh/100mi for a given mph:
mph^2 * 0.00273
And the metric folk: kWh/100km for a given kph:
kph^2 * 0.00066
Okay, so now we can say, at 70mph, the drag force is 70*70*0.00273 or about 13.3kWh/100mi. (8.3kwh/100km).
So, of the 27.9kWh/100mi consumption rate, 13.3kWh/100mi is from drag.
This leaves 14.6kWh/100mi that we won't change as speed changes*.
(9.1 kW/100km)
Now, finally, for the OP's question, how does the range change at 125mph?
125*125*0.00273 = 42.7 kWH/100mi
This is the new drag force to replace the 13.3kWh/100mi at 70mph.
Add the 14.6 kWh/100mi and we're at 57.3 kWh/100mi. (35.8 kWh/100km)
Going back to battery energy of 83.7 kWh divided by 57.3, and times 100, we get....
146 miles (234 km)
----------------
*This 14.6kWh/100mi does likely change some with speed. For example, there are some time dependent energy uses such as AC that improve this number at higher speed. Rolling resistance may change some as tire temperature changes from the different speed. But as others have pointed out, the drag is by far the largest factor...and also most straightforward to just calculate.
sorry to say this but if you are on a road trip and need to maximize your range I've found the sweet spot to be 70-75 MPH. when I know that I am not stretching the range limits I will mash the pedal more.
Had both then. Turbo Aeros on sport efficient tires.
Ha no. 90 mph you get maybe 190 mi range. Widely shared here.
The difference in the power consumption you are seeing may result from where you are measuring the power. For the system as whole P = F * v where P is the power in watts, F is the total drag force and v is the velocity. For similar cars, this should be similar. But if your power is measured as the draw from the battery for a given speed, P = V * A, then different motors and drive trains will use different amounts of power to achieve the same speed even if the cars have similar aero.
