Don't let the cars parked in front of your home occupy too much of your attention, rather, put your energy into those things you can control, and which are, quite frankly, more important.
Have you made your lawn nice and clean?
Does the paint on your house look good?
Is the interior warm and inviting?
Could potential buyers walk in and easily imagine moving right in?
Is your home priced right for your area?
Is your home being advertised to attract all the willing and able buyers?
These atre the things that will sell your home. Potential buyers will understand that cars have to park on the street.