Merlinski, a couple of points.

Xara's SVG format is against version SVG 1.1. Perhaps Gran Turismo requires later?

The transforms are not for the object; the <g> tags refer to groupings.
The first one is just a maker as it is wrapping nothing.
The second one, as far as I can see, is handling the original location of the shape in relation to the layer it came from.

In later versions of the Xara Desktop Application, shapes are rendered as embedded SVGs. Everything is compacted down and the SVG is presented without all the faff you have encountered.

See if GT can handle this:
Code:
<svg style="position:absolute; left:0; top:0; width:100%; height:100%; overflow:visible; viewBox: 0 0 231 267; pointer-events: none;">  <linearGradient id="xr_svgg1" gradientUnits="userSpaceOnUse" x1="115" y1="62" x2="115" y2="203"><stop offset="0%" stop-color="#00FF03"></stop><stop offset="100%" stop-color="#FF0000"></stop></linearGradient>
  <path d="M 115.61 0 L 0 66.75 L 0 200.24 L 115.61 266.99 L 231.22 200.24 L 231.22 66.75 L 115.61 0 Z" fill="url(#xr_svgg1)" stroke="Transparent" stroke-width="0" stroke-linecap="round" fill-rule="evenodd" pointer-events="visible"></path>
 </svg>
then you might need to be on the latest version. For path nodes, it outputs 2 d.p. rather than 3.

I copied my SVG into a Blank Photo template and Exported to File from there; it lost the Page background group. I doubt if that helps you much.

My generator of choice is Boxy SVG.

Acorn