The 914 has both good and bad points from a safety point of view.
The bad ones are obvious. The car is
very small, which makes it hard to see when people are used to looking 10 feet off the ground for the other SUVs and Mac trucks. It is also built of fairly light-weight (and thin-gauge) metal, which is not as strong as your average old Yank Tank. The main things that prevent side intrusions (say, SUV bumpers or even Honda Accord bumpers!!) are the longitudinals, which are below the level of most of those abovementioned intrusions. Get hit from the side and you'll be very unhappy.
The good points: The front trunk, rear trunk, and even the engine bay are crumple zones. I've seen 914s that have taken some terrific wallops in the front or the rear and had the occupants survive with relatively small injuries. And some with not so small injuries. But from those two directions, the 914 actually is pretty decent in a collision. Especially when compared to most 1970-vintage "sports cars".
The 914 also has "active safety". It is small enough and agile enough to get out of the way of impending accidents. But the driver has to be aware of his surroundings and has to know what to do when trying to avoid such accidents, or Bad Things will tend to happen.
So, is a 914 safe enough for a 16 year old? I don't really know. I'm tempted to say "Sure, go for it!" But I'm not a parent...
Buy it now or later? Yes, that's what you should do.
If you want a father-and-son type project, get one now and start working on it. It always takes longer and costs more than you think it will. If you're looking to spend less money in the long term, get the best 914 you can right now. Get a friend to drive it every month or so--if you do the driving you may very well get hooked and need to buy
another 914 for the son.
If you can't do that, wait until the boy is almost 16 then buy the best 914 you can. Don't be afraid of spending top dollar for a 914--you'll save every penny of that and more from not having to repair everything. That really is the least-expensive way to go.
I feel that 914 values have already hit bottom and are climbing again, albeit slowly. So you'll pay a little more if you wait, but you won't have to maintain the car in the meantime. And you won't get hooked on it as noted above.
Did I mention that these little cars are addictively fun???
--DD