Execucar is unreliable. They are regularly late for airport pick ups. If you are landing in Phoenix you should call another company. Waiting for an Execucar pickup doubles the time to get to the hotel because they make you wait at the curb for over 30 minutes in the Phoenix heat even when you have a reservation.
It is ridiculous that they commit to pick you up at the curb within 5 minutes of calling for pickup (this is on a prereserved ride), and then they show up 30 minutes later. After the third time this occurred, I called customer service to complain and ask for a refund. They waited 2 weeks, called me back and asked for more details and asked what I wanted for compensation. I told them I wanted a refund. They then took another 2 weeks to call me back and wasted my time by asking all the same questions again and then saying they couldn't offer me any compensation.
I have never had a worse transportation provider in my life, and I've had some pretty bad transportation providers.