4 ms·

> Once, after Mr. Puglia had driven 35 miles to an ice rink, his range fell by 73 miles. Another time, a 60-mile jaunt reduced his range by 110 miles. I've fou

> Once, after Mr. Puglia had driven 35 miles to an ice rink, his range fell by 73 miles. Another time, a 60-mile jaunt reduced his range by 110 miles. I've found that the range estimate in my Ford CMAX (PHEV) is highly sensitive to recent driving conditions. For example, I drive one-pedal and am more conscientious about regeneration than my wife. When I drive the car after having been the last driver, the estimate is perhaps 20% greater than if I drive after she drove it. The result is that the range can drop by a lot even with relatively short trips. In some ways this is bad — it would be better if the vehicle showed accurate range estimates from the time you turn it on. This could be optimized by taking temperature into account more aggressively (I imagine Ford already accounts for it to some extent). But in other ways, there's no way for a vehicle to know if you're going to be heading uphill or downhill on your next trip, or if you're taking the freeway or city streets. It sucks when range estimate swing wildly, but it's possible that this is better than the alternative — that it remains too rosy for too long, and then you're screwed.

ryandrake 3y ago
I wish cars would stick to measuring what can be accurately measured, and stop trying to be so clever, but it seems that ship has long since sailed. Heck, my 15 year old gas car even tries to estimate range in miles, when it can't possibly know future driving conditions, speeds, hills and valleys, brake usage, and so on. Just show fuel level--at least that can be semi-accurately measured. "Range" is such a misfeature but drivers have long since shown with their wallets that they are fine with being lied to. Some might argue: Well, nobody cares how much fuel is in their car or how many amp-hours are left, they care about range. Sure, but these systems are not providing range. They're providing wild-ass guesses based on unreliable inputs and incomplete data. Better to not provide the value at all than to give what's essentially a random guess.
- gnicholas 3y ago
  The variance in range of an EV is very different from in an ICE vehicle. My ICE doesn't seem to vary much based on temperature, whereas my PHEV really does. This is partly because of the way the battery is discharged itself, and partly because cold weather necessitates heating. ICE vehicles have a ready-made heat source, whereas EVs do not. All this to say: I appreciate the mileage estimate in my ICE, but I've had to learn how my PHEV works to be able to interpret it fruitfully.
- bandyaboot 3y ago
  I disagree with this. I find the “range” to be a useful data point especially as the fuel level is getting low. As long as you have a general, realistic understanding of what it’s telling you. I don’t know specifically how the number is calculated, but my assumption is that it has got to be based on some sort of moving average of fuel consumption. With this I can keep an eye on the number and allow my human, good-at-pattern-recognition brain to do its thing and use it as an input to whatever decision I need to make. Personally, I find it a slightly better source of information than a simple fuel gauge that’s getting low.
photoGrant 3y ago
Just lie to me and tell me the worst case scenario. If the customer focused lie puts you in a marketing bind because the truth is you can't meet what you're alleging to sell... That's your problem. As a customer, I don't need the anxiety of estimations being off by almost 100%. What use is that for me? It's only use is to minimally meet your marketing book of lies to sell technology that isn't quite there yet and put the onus, expense, and anxiety of this transition onto the customer. Put it this way, I've never ended a journey and been annoyed I had more miles left in the tank than it promised. But you can bet the opposite would have be stranded and screaming on a highway somewhere instead. Why do you want your customers to retain that angst against your brand? Cars of all things are long term, emotional investments. Screwing one customer and they don't stay quiet. Either way, we're car beta testers now.
- schiffern 3y ago
  >Just lie to me and tell me the worst case scenario. What do you consider the "worst?" 99th percentile? 99.9th percentile? Worse than that? The straightforward worst estimate is to assume you'll immediately climb the highest grade road on Earth, against the strongest headwind on Earth, in the coldest conditions and worst precipitation ever recorded on Earth, until you run out of battery. That's probably not the calculation you actually want, however. Ultimately the question is like tuning sensitivity vs. specificity in a medical test. There's a simple answer that can eliminate one class of error (set the tuning threshold to one extreme), but despite that appeal actually it's not the correct answer most of the time. With the tuning set to the 99th percentile, the computer will underestimate range 99 times for every one instance where it overestimates range. That's not the absolute worst, but is sufficiently worst for you? Or do you want it even more pessimistic? IMO the answer is cars should simply decline to provide any range estimate at all (just a battery percentage) until the user inputs a destination. None of this (fundamentally intractable) "guess if they're gonna drive up that nearby mountain or not" problem...
  - photoGrant 3y ago
    I consider it to be whatever the clever people who design this stuff decide, so that my average use of a vehicle in all potential climates and conditions is factored. Why do I care? My driving habits and conditions haven't changed, nor has anyone else. Things might be slightly warmer, colder, steeper or shallower, but they aren't an infinite high grade against the strongest headwind on earth. That's the kind of lazy talk I'd expect to hear from an engineer who doesn't want to solve the problem and instead would rather see me as a customer suffer.

ryandrake 3y ago

I wish cars would stick to measuring what can be accurately measured, and stop trying to be so clever, but it seems that ship has long since sailed. Heck, my 15 year old gas car even tries to estimate range in miles, when it can't possibly know future driving conditions, speeds, hills and valleys, brake usage, and so on. Just show fuel level--at least that can be semi-accurately measured. "Range" is such a misfeature but drivers have long since shown with their wallets that they are fine with being lied to. Some might argue: Well, nobody cares how much fuel is in their car or how many amp-hours are left, they care about range. Sure, but these systems are not providing range. They're providing wild-ass guesses based on unreliable inputs and incomplete data. Better to not provide the value at all than to give what's essentially a random guess.

gnicholas 3y ago
The variance in range of an EV is very different from in an ICE vehicle. My ICE doesn't seem to vary much based on temperature, whereas my PHEV really does. This is partly because of the way the battery is discharged itself, and partly because cold weather necessitates heating. ICE vehicles have a ready-made heat source, whereas EVs do not. All this to say: I appreciate the mileage estimate in my ICE, but I've had to learn how my PHEV works to be able to interpret it fruitfully.
bandyaboot 3y ago
I disagree with this. I find the “range” to be a useful data point especially as the fuel level is getting low. As long as you have a general, realistic understanding of what it’s telling you. I don’t know specifically how the number is calculated, but my assumption is that it has got to be based on some sort of moving average of fuel consumption. With this I can keep an eye on the number and allow my human, good-at-pattern-recognition brain to do its thing and use it as an input to whatever decision I need to make. Personally, I find it a slightly better source of information than a simple fuel gauge that’s getting low.

photoGrant 3y ago

Just lie to me and tell me the worst case scenario. If the customer focused lie puts you in a marketing bind because the truth is you can't meet what you're alleging to sell... That's your problem. As a customer, I don't need the anxiety of estimations being off by almost 100%. What use is that for me? It's only use is to minimally meet your marketing book of lies to sell technology that isn't quite there yet and put the onus, expense, and anxiety of this transition onto the customer. Put it this way, I've never ended a journey and been annoyed I had more miles left in the tank than it promised. But you can bet the opposite would have be stranded and screaming on a highway somewhere instead. Why do you want your customers to retain that angst against your brand? Cars of all things are long term, emotional investments. Screwing one customer and they don't stay quiet. Either way, we're car beta testers now.

schiffern 3y ago
>Just lie to me and tell me the worst case scenario. What do you consider the "worst?" 99th percentile? 99.9th percentile? Worse than that? The straightforward worst estimate is to assume you'll immediately climb the highest grade road on Earth, against the strongest headwind on Earth, in the coldest conditions and worst precipitation ever recorded on Earth, until you run out of battery. That's probably not the calculation you actually want, however. Ultimately the question is like tuning sensitivity vs. specificity in a medical test. There's a simple answer that can eliminate one class of error (set the tuning threshold to one extreme), but despite that appeal actually it's not the correct answer most of the time. With the tuning set to the 99th percentile, the computer will underestimate range 99 times for every one instance where it overestimates range. That's not the absolute worst, but is sufficiently worst for you? Or do you want it even more pessimistic? IMO the answer is cars should simply decline to provide any range estimate at all (just a battery percentage) until the user inputs a destination. None of this (fundamentally intractable) "guess if they're gonna drive up that nearby mountain or not" problem...
- photoGrant 3y ago
  I consider it to be whatever the clever people who design this stuff decide, so that my average use of a vehicle in all potential climates and conditions is factored. Why do I care? My driving habits and conditions haven't changed, nor has anyone else. Things might be slightly warmer, colder, steeper or shallower, but they aren't an infinite high grade against the strongest headwind on earth. That's the kind of lazy talk I'd expect to hear from an engineer who doesn't want to solve the problem and instead would rather see me as a customer suffer.