Yeah, we all watch youtube videos of wicked fast street cars but this isn't common...I agree that 11s are rare for a street car...and if someone tells you that their old muscle car runs 11s, you can figure out pretty quickly if they're full of beans.
The easiest way is tires- it's extremely unlikely that a car running BFG Radial T/As (which 90% of old muscle cars have) will crack much below the 13s. They have a speed rating of "T" at best which means that they'll possibly come apart 112-118 MPH...you need a damn lot of traction off the line to trap 112 and be in the 11s which these tires simply do not offer.
Maybe they have slicks at home? Ok...you can still eyeball their equipment pretty quickly. If it's a big block Duster with Indy heads and a narrowed rear...ok. Anything much less than that and they're blowing smoke.
Yes, it's very possible to get stock looking muscle cars into that range...but this usually requires fully balanced/blueprinted motors that are stroked/bored and pretty much every trick in the book thrown at them. It's big bucks.
FWIW, I have a mostly stock Coyote Mustang in the garage next to the Dart. It has 3.55 ratio, sticky tires, exhaust, tune...probably a solid mid 12s car (with my dad driving at least...probably not me!) and it feels plenty fast. Running there with a 3500lb car takes 285/summer tires, modern fuel injection, 11:1 motor with variable timing that revs to 7000 RPM. If my Dart is ever that quick, I'd be thrilled.
