It is NOT transmission fluid leakage!
It means the transmission actually stops working (without any warning!). If you know any mechanic, ask them what is transmssion failure. If you are driving on the highway, and the temperature is minus 20 outside, then transmission failure is the most dangerous.
To replace transmission is an expensive job, more than thousand dollars.
If you want to "开4到5年", I think you can consider LEASE a car. All cars no matter what brand name should be trouble free in the first four years. You just return the LEASE car after you have finished your lease. And if you want to keep the car, then you have an option called "Buy Back", which is the car residual value after four years. Those cars with higher residual value are cheaper to lease. If you want to "把贷款还清就打算卖掉再买新的" then LZ should look for a car with better retain value. This, LZ can do some research yourself, it is easy to find car residual value from internet.