First of all, there's a huge variety of luxurious rental vehicles in Carinthia. What you end up opting for is largely dependent on what you're willing to spend and the activities you've got planned. Specialty vehicles are hard to beat if you're all about comfort and class. If you want to treat yourself, why not book a high-end SUV, or perhaps a flashy medium-sized vehicle? Otherwise, if you just need a set of wheels to zip around town in as efficiently as possible, maybe go for an economy compact vehicle (or something else that won't burn a hole in your wallet).