I've got mixed feelings... i like the concept... i know of some 80's jap cars that had a ringer that you could turn on/off with a key for if the car exceeded a specific speed limit (subaru XT is what i'm thinking right now... think it was just over 45mph)
my kids won't need it... they'll start in a car that will be lucky to hit 80mph... like me :)...
i learned to drive in a '82 diesel 4x4 suburban that 6.2L had a massive 130hp and weighed nearly 3 tons... you got nowhere fast and it had a built in speed limiter... go over 45mph and it started vibrating due to the slightly bent axle... (which replaced the VERY bent axle while we lived in panama) driving this taught you to know where your vehicle was at all times (am i hanging out into traffic on either end?)... the crappy brakes thought you to keep your distance and the lack of acceleration taught you to wait for a VERY large opening before pulling out into traffic...
i'm not saying this is a good car for others to learn in... but i'm still glad to have learned with such a beast... I have no problems hopping into a large box truck or driving any other large vehicle...
the 1st car i ever owned/bought was a '85 tercel with a MASSIVE 62hp... (although at just about 1ton and with a 5spd it was quicker then the suburban...) it struggled to keep to 60mph... forget about 80mph... it was my 'rents car before mine and it did... we took it 1000 miles away to MI a few times... it wasn't fast but it got us there...
i still miss it... if i could find a straight one i'd snap it up and toss in a 4afe...
my kids will likely own something along the lines of a CRX, miata, Mr2, or an MGB... something along those lines... small, reasonable power and 2 seats...
as for youngins and the interstate... with a motorcycle permit you are limited to daytime riding and no interstates... I know in FL if you are younger then a certain age you even have a special tag which indicates so... there are also special tags for convicted DUI drivers... i see no problem with these types of things across the board...
the one problem i do have is the thought that someone (big brother kinda thing) would think suddenly it would be a good way to enforce certain things... and it would be an across the board type of things...