I am searching for a Barracuda model !

There were not alot of 65 Barracuda models made, and still aren't. AMT made a kit and an assembled promotional model in 1/25 scale. The kit is seldom seen, and the promotional model (usually seen in light non-metallic blue) is rather expensive. Since you likely don't attend big shows like Fall Carlisle or the Mopar show at Carlisle, your best bet would be to watch for them on E-bay. They do come up frequently on E-bay. There was also a 66 Barracuda model and promo made. The 66 promo is usually seen in pale yellow, and this was also in 1/25 scale. Another manufacturer made a 1/32 scale 65 Barracuda model, but I don't remember if that was Monogram or Revell. Eldon may have made a 1/32 scale slot car of the 65 Barracuda, but it would likely be a pretty crude looking model. Ideal made a 1/43 scale Motorific battery powered slot car that was fairly accurate in appearance and can be found frequently on E-bay for a fairly reasonable price. Sabra made a 1/43 scale diecast toy 66 Barracuda. Highway 61 recently made or possibly still makes a high detail diecast 1966 Hurst Barracuda "Hemi Under Glass".
Since you're in germany, your best chance to find what you're looking for will be E-bay.

Heres an e-bay auction for a red 65 Barracuda promotional model
http://cgi.ebay.com/1965-PLMOUTH-BA...139?pt=LH_DefaultDomain_0&hash=item19c8115b83

Heres an auction for a Motorific 1/43 scale 65 Barracuda body. I don't like the roof painted black on the red one. It waqs also available in a solid turquoise, and in blue with a white racing stripe centered over the hood roof and trunk. The blue and the turquoise ones look better since they don't have the black roofs.
http://cgi.ebay.com/1967-Ideal-Moto...160594104437?pt=Slot_Cars&hash=item2564279075

Heres an auction for a 1/18 scale diecast 1966 Hurst Hemi Under Glass
http://cgi.ebay.com/1-18-1966-Hurst...36357?pt=Diecast_Vehicles&hash=item2313341785