There are a few options to create big splashes.
1. in the Physic Properties settings of the Liquid Domain is an option called Fluid > [X] Liquid >
[X] Fractional Obstacles. When it's enabled obstacles will create much more splashes.
2. you are dipping the car into the water ;-) There won't be big splashes. You need to throw the car into the water. Change the keyframes so the car will drop from about 20m height within the first 20 frames. It needs some speed.
Rigid Body physics also works.
3. the higher the Fluid > Settings > Resolution Division value is the more liquid the fluid will be. But this also increases simulation baking time and the number of vertices. This value depends on the size of the liquid domain.
In the example, the dummy car is scaled down to 0.5 to make the splashes look bigger (just a test). If you have a car in real-world size, it might be better to leave the car alone and double the size of the liquid domain and the liquid source and adjust the Resolution Division value. Don't forget to apply the Scale to the objects with Ctrl+A in Object mode.
Increasing the FLIP Ratio might be another option (not tested). The default value is 0.970, and the max is 1.0. Not sure if it has a big impact.
Examples for different Resolution Division values
96 Resolution Division, several minutes baking, 170k vertices, lag in viewport (2 frames/sec playback speed in solid mode)
48 Resolution Division, a few minutes baking, 41k vertices
32 Resolution Division, quick baking, 17k vertices, low splash and it goes in opposite direction
animation with 40 Resolution Division