For the roads I drive it would be a complete faff making sure it was set at the right speed each time, partly due to driving a range of vehicles each with a different implementation as well so I don't have it down to muscle memory on any one vehicle. Some of the roads I drive within a mile go like 60, 40, 30, 50, 30, 60, etc. as well.
Personally have never had a problem keeping a constant speed on dual-carriageways or motorway aside from the occasional hill - the CVT on the Qashqai can need a bit of attention going up hills so speed doesn't drop out. Most vehicles I drive sit nicely at 60 or 70.
Wouldn't say no to having a speed warning activated by the current detected limit though, for some reason none of my vehicles have that feature despite having the current speed limit indicated on the dash which is surprisingly accurate.
The ID.3 had adaptive cruise with speed limit awareness, so it would follow the speed limit or car in front, it made using it much less of a faff since you enabled it once and it did what I wanted as it transitioned between limits.
I find people on motorways will drift in speed up to 5+ MPH over time, which is why I often get annoyed that you are creeping by someone, with a 2-3mph delta and suddenly they speed up 5mph, so I drop back in behind them, then they slow down by 5mph, so I move out, and the cycle repeats..
I'm amazed at the fuss it's caused. I've not met anyone that actually lives on these roads complaining, which is ultimately who this should be for.
Its very dependent on the area.
My old village (well it's 2 villages with a main road running through), most houses are not on the main commuting/thoroughfare road, they are all down side roads). I popped in last weekend to see our old neighbours and universally in the area the speed limits have been causing havoc, there is a local action group who have garnered support for the petition and they don't seem happy.. This is a 30/50/NSL gone pretty much to a 20/30, there are 2 small 40 sections, but as mentioned below, people are
Some of the issues they've voiced on top of the normal complaints:
1. Just time wise, many now have to spend £80 per child per week on extra child care, they can no longer drop their kids off just before 9AM and get to work by 9:30 in neighbouring towns, it's taking around 20 minutes longer on a 30 minute trip.
2. 20 is closer to 15/16 mph since you go by the slowest vehicle, and some peoples speedo's are unwillingness to do the actual limit since its 'not a target' almost feels like malicious compliance.
3. The 40/30 sections are also clogged with people doing 15/16 mph as they ignore the limit change, so you have a good stretch which if they ignore the next section in to the countryside is quite a long way.
4. There has been a noticeable uptick in people pulling out unsafely, last second when there isn't a safe gap, probably because they don't want to wait until the end of the long queue of traffic.
5. Cyclists are more at odds in terms of being overtaken, they will undertake cars on the declines as doing >20 is easy, and cars then (slowly) overtake on the inclines when they slow, and that comes from cyclists themselves..
6. Pedestrians are also chancing it more crossing the road, they don't wait for a safe gap, they just walk between the cars doing 15/16 mph
7. MPG has markedly suffered, not sure if just non optimal gearing, i.e. most people are in 3rd/4th especially with so many doing quite a bit under 20, rather than top gear, or if its the constant modulation of a train of slow moving cars.
I experienced the delight of being stuck in a 20+ car convoy behind someone doing very much <20 and saw some pretty dangerous overtakes by a handful of cars that after 3 miles had had enough..