CX-90 True Mileage - What you need to know
Hello folks, it's been about three weeks since I picked up the 2024 Cx-90 Premium PHEV. This vehicle came off a lease from a corporate owner and has approximately 28k miles on it.
Since getting it, I've been on a relentless pursuit to maximize the miles per gallon figure. I've been browsing multiple reviews/recommendations from users and YouTube on how to achieve this. As of yesterday I've reached 39.4 mpg (the photo shows 39.2 since it was taken a little before my final stop). Along the way I've also deduced what each of the key items on the instrument cluster are and how they affect the final mileage you get. I'll be sharing all of my learnings in this post. Please consider that these are all from my observation and deduction and if anyone has dissimilar experiences or formal publications that contradict what's mentioned, feel free to share. Also for anyone reading outside the US, all units of measurement/currency here are truly irrelevant to what you'll know at the end of this read so please bear with me.
Additionally please note that this is based on my daily commute to work and back, which is 18 miles one way, comprising of approx 2 miles of city driving on very high gradient roads and 16 miles of freeway with medium congestion. I have regenerative braking set to high and I charge my car to full once per each round trip. And I drive in normal mode.
Alright to get started you'll notice I've labeled all the key items on the instrument cluster in the posted image. We'll go over each of them.
EV Gang - This encompasses three key indicators that always appear together and that is the reason I call them a gang. Let's look at the three items A, B and C individually.
A. EV Zone - This appears as a solid purple bar on the Power indicator dial whenever the car is using the electric motor for power. Think of the power dial's behavior as the RPM dial on a gas car. The needle jumps the harder you press on the pedal. As long as the needle stays inside the EV Zone, the car will remain in EV mode.
B. Maybe EV Zone - This appears as a dashed purple bar on the Power indicator dial right where the EV Zone ends. When the needle reaches here, the car is preparing to transition to use the combustion engine.
What's important to notice is that the total length of A + B is not always the same. At lower speeds it is longer, whereas at higher speeds it is shorter. I'll explain why but first understand what it implies. A shorter length means you're more likely to switch over to gas with a little more request for power (by pressing the pedal more making the needle jump), whereas a longer length implies you're less likely to switch over to gas when there's a request for more power.
To explain why let's consider the case when you're in the city stopped at a red light. The EV Zone is long because even if you press the pedal harder than usual, the car knows it's better to get you from 0-30 mph using the electric motor than the gas engine. However, if you're driving 60 mph on the freeway, the EV Zone is short because the car understands that a press of the pedal to take you from sustained 60 mph to sustained 70 mph is better achieved with the gas engine.
Finally, C. EV Indicator - This is pretty much self explanatory as it comes on when the car is using the electric motor
D. Charge Zone - The needle dips here when you are in regenerative braking. Whenever you take your foot off the pedal, the cars momentum feeds back into the regeneration system, slowing down the car and capturing the energy back to be stored in the battery. Regeneration can be set to normal or high from the EV settings in the console.
E. Pure EV Range - This indicates how far you can go using only the electric motor. This is also only present when you have some EV charge (Label I). I call this pure EV Range because this range does NOT factor in the miles recovered from regenerative braking (I am mostly sure of this). The evidence behind my conclusion is a full charge shows about 22 miles of range. Then after a 18 mile drive, I still have 12 miles of range left. This indicates a recovery of 8 miles of range out of 18 or an ~44% range recovery which did not factor in.
F. Gas Range - This indicates the range of your vehicle excluding the EV Range, considering only the gas engine and regenerative braking. I will not dive too deep here as I haven't experimented enough to comment.
G. Hybrid Efficiency - Okay this is a big one. This number is affected by how your gas engine performs, how much charge you have in the battery, how your electric motor performs and your regenerative braking. Firstly, the effect from gas engine efficiency is a no brainer, like any gas vehicle. But to explain the rest of the factors you'll have to look at Diagram 2. It has two arms, one originating from the EV Charge and one originating from the regular fuel. Let's say you had no charge at all, then the EV arm is fully eliminated and the gas engine + regen braking will give you an ~25 mpg. However, what's interesting is the EV arm of the diagram. What it practically means is that you are converting battery charge to hybrid efficiency. By how much? That is dependent on the two variables along the way, i.e. electric motor efficiency and regen braking. But that's not the fun part here. Notice hybrid efficiency is denominated in "miles per GALLON". None of those words factor in battery energy. Therefore, the more you stick to the EV arm of the diagram (by not using gas) the higher your number can go. I intend to test this to see how high it can realistically go but theoretically it can be infinite.
This brings us to the most significant conclusion of this whole adventure. In combined systems like PHEVs, a metric like mpg ignores entire arms of the energy usage flow. It is inadequate because you are paying for two different forms of input energy (gas and electricity). Therefore the correct metric would be "miles per dollar" since what you are essentially putting in are dollars just in two different forms.
What is the miles per dollar of this vehicle? I don't know, that's your homework. I haven't done the math yet. But this explanation forms the basis of your pursuit of efficiency. Now let's wrap up the last few.
H. Electric Motor Efficiency - This indicates how efficiently your electric motor is converting the battery energy to actual mileage. If you press on the pedal too aggressively it'll go down and if you are gentle with it, it'll go up.
I. Charge level - The important thing to note here is that this does not show the true hybrid battery charge, unlike mild hybrids like the CRV which shows you a non zero value. This will only go up with plugged in charging and keep goin down at all other times the vehicle is using the electric motor. But this going to zero does NOT mean the mild hybrid mode of the vehicle is non-functional. We just don't get to see that battery reserve.
J. Gas Level - And finally the gas level. Well it's how much gas you have. That's all I got.
Hopefully, with these key bits of information, you'll be able to go on your own set of experiments to see what you can do with this vehicle. Now go, be free, conquer the world or whatever.