Fastest Spacecraft Ever?!?, Which one is it? Options

[Toma B]

There was statement that recently launched New Horizons is the fastest spacecraft to leave Earth. The velocity was 16.2 km/s relative to the Earth according to "Jonathan's Space Report".

After the Star 48B burn, the payload had reached escape velocity not only with respect to the Earth but also relative to the Sun (The velocity was 16.2 km/s relative to the Earth and I estimate an asymptotic velocity of 12.3 km/s, corresponding to 42.6 km/s relative to the Sun...

So:
New Horizons is fastest to leave Earth at 16.2 km/s (relative to Earth).
Voyager-1 is fastest to leave Solar System at 17.374 km/s (relative to Sun).

Now that is OK. but what is this?
Today's "Astronomy Picture of the Day" features launch of New Horizons and in text bellow image is one particularly interesting link to "Guinness world of records"...
Guinness world of records;
There "Mr. Guinness" claims that the fastest spacecrafts ever, were two Solar probes "Helios 1&2"...According to him those spacecrafts had speed of 252,800 km/h which is staggering 70.2 km/s...BUT RELATIVE TO WHAT?????
Can somebody explain this?

[ljk4-1]

My concern is that the VSE is going to become Apollo Mark 2, where it takes
away resources for real science missions just to put a few extra humans on
the Moon for slightly longer stays.

Then the politicians of 2020 or so decide it is not worth the effort, or the public
gets bored again, or both, and we end up with a few more flags and footprints,
the Moon is abandonded for another 40 years, manned Mars missions get
pushed even farther into the distant future, and robotic planetary missions
lose the momentum they had regained in the 1990s and 2000s. All for yet
another stunt to show the world just how great the USA is.