There's no train connection with Ankara Esenboğa Airport.
Car and bus
Ankara Esenboğa Airport is situated 28 kilometers northeast of the Turkish capital's center. The airport is easily accessible by rental car; from the ring road (O-20) around Ankara, Özul Blv leads to the airport. The way is clearly signposted.
City busses (line 442) maintain the connection between the airport and Ankara's central bus station. Bus company Havas maintains a shuttle bus service with the Turkish capital, with stop-overs in Cubuk, Pursaklar, Haskoy, Kecioren and Etlik (traveling time: approximately 50 minutes).
Car rental Ankara Airport
Counters for car rental can be found in the Arrivals Hall. Four rental companies are present at Ankara Airport: Avis, Budget, Hertz and National. You can also book a rental car using the services provided by EasyTerra; they compare the rates of several providers in a single quote.
Outside the Arrivals Hall there are many taxis which all have a meter. A taxi ride from Esenboğa Airport to Ankara Center costs about 45 Turkish lira.
The large parking garage at the airport is directly connected with the terminal. There's also a large open-air parking lot. On the airport's website you can calculate how much you need to pay to park at Ankara Esenboğa Airport.