I ggogled it and found some more info and photos on the T-Mobile site:
http://www.t-mobile-team.com/cms/tmoteam/en/tourdefrance/templateId=renderInternalPage/id=62164.html

 On 7/25/05, Brian Wasson <briwasson@verizon.net> wrote: 
> 
> With all this talk about VWs and the Tour de France, I forgot to
> mention a cool VW sighting in the Tour's "Caravan." (The
> Caravan consists of sponsors' cars, floats, trucks, etc. that come
> through the day's stage route about an hour before the riders.)
> T-Mobile had two very nice-looking vintage VWs in the Caravan: a bus
> (loaf) and a bug, both fully restored. They both featured the T-Mobile
> "chime/ring" that you hear on the commercials as their horn sound. I
> wasn't fast enough to get a full photo of the bus, but you can see the
> back end in this photo:
> http://www.brianwasson.com/tdf2005/pages/DSC_1909.htm
> 
> Brian Wasson
> Abington, Pa.
> 1988 Westy
>