Virtuemart tracking extension is available. It was tested on over 1 month, and finally we choose a Virtuemart tracking in php using the __utm.gif server-side request to Google Analytics instead the javascript. It works simply perfect, and it uses this unique function compared to all other extension. The php server-side tracking lets this extension to track everything: both paypal or similar automatic IPN (istant payment notification) both a manual changing of order status by the administrator, in case of payment as bank money transfert, or similar. The other big difference, is that we create a transactions database queue, to avoid incompatibility with other extension, so the tracking is made at the end of the page rendering, after all other plugin funcitions. It also track normal users traffic on website, using classic javascript code. It's a professional solution.