It's like a vending machine – but instead of a bag of chips, you get a car. That's how Carvana (NYSE: CVNA) co-founder Ryan Keeton explains what his Phoenix-based company has built beside I-440 in Raleigh on Navaho Drive, which opened Wednesday. Carvana is capitalizing on the shift from brick-and-mortar to e-commence, he says, pointing to how large-scale players such as Amazon have changed the shopping experience forever. When it comes to big purchases such as vehicles, however, his team's research…