Ftraven

To begin, an aerodynamic vehicle will be highly streamlined. Consider the Volkswagen XL1 concept car, which has a very low drag coefficient of just 0.31. It primarily has a buttery smooth nature free of sharp edges, valleys, and any other function that could trap air and cause turbulence.
Second, the very aerodynamic car has a flat bottom, which increases the Venturi effect, no sharp edges or corners on the line leading to the roof, and a fastback design, which reduces turbulence.
Since the bottom of the engine bay is closed off, a flat and smooth floor enhances cooling by redirecting air towards the engine through a series of vents. This is why driving-oriented vehicles, such as the Mazda 3, have a sealed-off undercarriage. Sure, it isn't easy to obtain, but it's perfect for boosting aerodynamic stability. Also, removing a car's bottom engine cover increases NVH. After all, the uneven shape of the engine's bottom and components found under a vehicle would have many rough surfaces.
Third, the external features of the vehicle, such as the door handle and side mirrors, should be rounded. Although re-directing air towards the wheel-bays can increase drag, it is a common feature on high-performance vehicles to help cool the brakes.
However, although installing aero aftermarket kits can reduce drag, an incorrectly mounted wing or a “too large” or “too ridiculous” aero kit would only increase surface area and drag.
This leads one to consider more cost-effective and practical everyday cars and why some of them can or may not be quite aerodynamic.
If you know anything more about the relevance of aerodynamics in cars, feel free to comment below