the Ariel D class is not comparable to the Zugo Rhino....D class has dual motors/all wheel drive.
You would not be slow with the Ariel D class i'll tell you that much, that thing is a beast.
I just checked out the Zugo, looks like it has a 750W motor, the D class has 2x 750W. It does seem as though the Zugo is a bit cheaper at 1800 verses the D-Class' 2400 but I would rather pay a bit extra for 2x the power, literally.