I was the one that started this thread and I still love the app. But in my opinion/experience the answer is yes. YMMV.
It was using 6% of my battery (iPhone X). I have disabled background on my phone and installed the app on an iPad that is always plugged in with background enabled. The way this app works, which is awesome, the iPad can do the work but the phone will still see all the data and have all the control it needs.
The developer might not think 6% is much, and many folks might not think it's much.
It can be a little tricky measuring load on an iPhone because it's 6% of the "work" it did. If the phone did nothing else but this app it will naturally be a higher percentage (because it has nothing else to do). If your phone is doing tons of other stuff this app might show very low. But I know what similar apps are using relative and it used more than I wish on my daily phone. Because of how iPhone presents battery usage it's very hard to compare one users battery usage to another.
I have put in a request to the developer to add a user controlled "Cap" of how often it's allowed to communicate. Even if that impairs some of the stats. I would prefer have that control. If iOS wakes the app every 1 minute, I want the option in the app that tells it to ignore "wakes" until it's been say at least 5 minutes. To use 6% of my battery it had to be communicating quite a lot. You can't make iOS call you faster/more often. But you can ignore requests to wakeup and process. Perhaps the developer feels any slower than it runs now would impair functionality.
Again, I still love the app and use it. But it does use a bit of juice. I've not seen any impact to the car.
