I’m temporarily renting a 2020 Chevy Versa. It has OnStar, but the subscription has expired. It handled the switch to DST perfectly. I’m totally guessing here: when I start the car, it attempts to get OnStar, and the “subscription expired” message invisibly includes the correct time, and the car updates the time from that.
I did try switching back and forth from various AM and FM channels to see if that might trigger the automatic DST update, but it did nothing. That was when I came to the assumption that it must solely rely on the now unavailable 3G or 4G cell signal.
I have an Amazon Echo that I have set up to go between the clock and weather. The clock automatically went on daylight saving time however the weather screen which also displays the time has stayed on standard time.
I drive a 2012 Chevy Tahoe, and its clock has never updated automatically. Its owner’s manual states that it doesn’t. Maybe it’s too old to do so, but it’s no big deal to push a couple of buttons to get it right. Meh, I deal.
My 2020 Outback requires a manual reset to DST, its a couple taps on the screen and a scroll in the settings to reach it. Whenever I travel across a time zone of course the car clock doesn’t change but if I have maps open on the scrteen it automatically changes there to local time.
Europe transitions at different dates than North America (to DST on the last Sunday in March, so later than America; and back to winter time on the last Sunday in October, so sooner than America). Could it be that your car transitions offline (i.e., does not pick up the date from the network but is simply programmed to change the clock at certain dates) and has, for some reason, been set to the European schedule?
Maybe the car radio has a date setting that it uses for DST changes, and your date is wrong?
Me too. The 3G/4G idea might explain past years’ behavior – the signals became rarer, but not completely gone, so in prior years on Day X after the change, I’d eventually drive by an increasingly rare 3G/4G tower and the time would update. Now, apparently that never happens because the old towers are not just rare, they’re extinct – the car might as well be trying to receive a telegram after Western Union completely folded up.
One more data point: the clock is now off by an hour and 3 minutes, suggesting it’s received no signal update for long enough (perhaps months) for the clock to drift, as old-school clocks will.
Interesting. I was erroneously assuming that DST was a US peculiarity, which has been subject to debate over its usefulness and legislative moves to abolish it.
Since my truck automatically connects to my phone via Bluetooth, I wish it was smart enough to synch the truck’s clock to the time on my phone. Unfortunately, it does not do this. 
I have an old landline house phone system (4 cordless receivers) and I noted once that the time reset when the first call came in after the time change. The caller ID system includes date and time, I presume.
I own a 2023 Toyota RAV4 Prime pluggable hybrid. It does not automatically update the clock for Daylight Saving Time. There is a DST selection in the settings on the main display screen.
I have wall clocks that get their time from WWV in Colorado, 1800 miles away. The reception only works at night. Even then, it’s poor. If this is how your car is corrected and you live on the east coast, and park inside at night,it may take a while.
WWV sends GMT which is not how most people configure the clocks in their cars. The wall clocks have a way to configure a local time zone that I din’t think I’ve seen in a vehicle. Of course, you can’t drive a wall clock across time zones, either.
Ironically, kinda, there are similar transmitters in Hawaii. Someone in Honolulu should have very, VERY good signal.
I would assume any clock that uses that would allow you to set an offset.
Though I don’t know how helpful that would be for Daylight Saving Time, since the offset changes then. I would hope any clock-setting signal would include DST info.
I’ve had one of those Colorado wall clocks for so long I don’t even remember if I had to configure it for my time zone. Don’t see why it couldn’t be taken on a road trip, though. I’ll have to try it sometime.
It’s an analog dial; it’s fun* to watch it reset itself on Daylight Saving Day if I happen to be up at 2am. It would be even more fun to watch it reset itself the moment I drive across a state line, though that seems a little doubtful (how would it know?)
*I’m easily amused
Why would it? The NIST does not administer time zones.
There is a public-domain database tz database - Wikipedia that you can load into embedded software, though.
Returning to the spirit of FQ though, I believe this is the definitive question-answering post of the thread (thank you @Francis_Vaughan). As far as my own car, it still hasn’t updated itself with any amount of driving around and radio use, so I must assume its sad 2014-era 3G receiver is waiting for an antiquated signal that will never come again.
OK, I checked and you are right: the NIST does recommend that manufacturers use the DST information in the broadcast time code, because a built-in database that cannot be updated may become obsolete. However, they acknowledge that there must be an option to disable or override this, as the rules for DST differ even among different parts of the United States.
That and DST are how we know OP’s car clock doesn’t use this mechanism.
okay, folks, I cannot resist an opportunity to post a link to a wonderful MPSIMS thread about a similar issue. (correcting the date, not the hour).
It’s a long and fun thread, about the poor Doper whose car did not know about leap years. (But he did get to celebrate the 99th of February, and beyond… 
)