Thank goodness they don't, because today's autos are cleaner, safer, more efficient, and more reliable. A good deal of this improvement is based on developments in automotive electronics (not to mention computer aided engineering refining and streamlining the auto design process.)
Onboard computing governs engine functions for performance, emissions, and efficiency, and safety features such as intelligent airbags and stability control are microprocessor enabled. But growth in auto electronics is also being fed by additional "convenience" systems such as multimedia and GPS navigation.
This growth is taxing automotive electrical systems in supplying sufficient, clean power when needed. Fortunately, electronics are getting less power hungry and generation is becoming more efficient, but the demands from "accessory overload" are catching up with these improvements.
However, there are methods available for smoothing out transients imposed on overloaded electrical systemsfor example by using ultracapacitors for bursts of power that won't drain batteries, obviating the need for perhaps an extra battery on board to keep up with the burgeoning demand.