I find the best and quickest way to carry a bike on a Gt is just put it on the roof and get some cheap bungees from the local pound shop. Just strap the bungees to the bike and then onto handles inside top of doors. The bike does slip around a bit, but if you put an old sock over the pedal and the handlebar end, it won't scratch the paint. If there's no bungees around, just get some sellotape and run it from passenger door, over bike through driver door, do it a few times just in case. Doing it this way makes sure there's no load on the rear screen, thus no damage to the GT!
GT 3.2 V6 - Q2, KONI FSD & EIBACH PROKIT, GTA REMAP, MICHELLIN PS3's, BMC CDA
159 SW 2.4JTDM TI - ALFATUNED, WIZARD BACK BOXES, KW V3 COILOVERS, NOKIAN WR A3/MICHELLIN PS3, PCA DYNAMICS ALIGNMENT.