When did Voyager-1 achieve Solar System escape velocity? Wikipedia's page on escape velocity puts the escape velocity for an object travelling out of the Solar System at ~525km/s. This figure is slightly higher than the tentative velocity of Voyager-1 at ~17km/s. 
Why is the vehicle spoken of as being on an interstellar course? When did the vehicle achieve Solar Escape velocity? What am I missing?
 A: 525Km/s is escape velocity w.r.t. The Milky Way's gravity at the position of solar system galactic radius. You aren't trying to escape the galaxy. Are you?
A: Escape velocity depends on what you're trying to escape from and how far away from it you are.
That Wikipedia reference makes that very clear.
As Sachin Shekhar pointed out, if you're in the vicinity of the sun, and you're trying to escape the galazy, you need 525 km/s.
If you're trying to escape the solar system, and you're at Neptune's distance from the sun, you only need 7.7 km/s.
When did Voyager 2 achieve escape velocity from the solar system? According to this diagram from Wikipedia, it occurred during its gravity assist from Jupiter.
Voyager 1 was probably not too much different.

A: Well, this is good news. It would be disappointing if they settled into a comet-like orbit, yet interesting to future humans who would see it return.
Just to confirm, this astronomy.com senior editor also says yes, they have both achieved solar escape velocity. I imagine moving gravity wells but can’t quite grasp how the slingshot effect works.
https://astronomy.com/magazine/ask-astro/2019/01/no-returns#:~:text=Take%20Voyager%201%20as%20an,(79%2C000%20km%2Fh).
