Safety versus cost.
4 years ago, my then 17 year old totaled my 190e 2.6 2 weeks after getting her drivers license. She t-boned a small Japanese sedan.
My replacement was the 124C. Hers was a 97 Ford Escort. She had three three rear enders with it before it finally succumbed to the abuse involved in sideswiping 3 parked cars at 2:00am with (thankfully) another girl behind the wheel( DWI of course).
One cost 2,000 cash to fix her car with no damage to the other car (Jeep Liberty). The next was a rear ender to a teenage girl making a left hand turn. Although damage was limited and the car was fully driveable, insurance company totaled the car which I bought back. Before the car could be fixed, yep, she goes back to college and hits another car in the rear. Toyota Avalon. So, 700 to fix the toyota and another 800 to fix the escort. The settlement from the second accident paid for the repairs to both the cars in the third.
As a father and human being, nothing made me happier than her and everyone else being uninjured in these accidents. As a car owner, nothing made me more frustrsated that one accident after another after another after another, especially in NJ where car insurance rates are out of sight.
Teenagers will have accidents. You want them safe. Personally, today, I'd get an old 190 2.3 (or a 240) in decent shape for a teenager. Not too big, not too powerful, but plenty able to protect passengers in case of an accident. IMO a 124 is a pretty big first car for a teenager unless you live in the country. Triple the thought for an SUV.
Hope the poster's daughter's Mustang wasn't a 5.0 5 speed!
"Most of the experience you get in life you get five minutes after you needed it." (unknown)
The joys of parenthood, eh?