Overall, the anime adaptation of 'karekano manga' is relatively close. Some minor details might be different for better visual presentation or to fit the animation format, but the core story remains intact.
The key to showing a smooth car ride in a cartoon is having seamless animation that shows the car gliding smoothly on the road. Plus, the sound effects of the engine and the wind can enhance the experience. And, if the car is interacting with the environment smoothly, like going over bumps without much disruption, that helps too.