How to get taxi for 15 pax from Xian airport to Sofitel Ramen Hotel?

Do you refer to Hotel Sofitel On Renmin Square?
If yes, one cab can allows three passengers. You need to have 5 cars. So you are suggsted to hire a mini van from the airport directly. You can find several car rental services near the airport. In addition, I heard that TravelChinaGuide has such pick-up service. They have professional drivers. And the price is acceptable. If interested, their contact information is traveltravelchinaguide.com.