The best bug and tar remover for cars is Stoner Tarminator. This is an amazing product that I discovered years ago, and hands down the easiest way to remove tar, bugs, grime, etc. from a cars exterior paint while being safe. Just spray on, and the grunge just melts away.
What makes Tarminator so effective?
“Tarminator breaks down the complex molecules found in tar and other sticky materials. This unique MicroActive cleaning technology gives Tarminator unequaled ability to remove even “baked-on” tar, grease, sap, and asphalt. Tarminator is the fastest and easiest way to remove difficult road grime. Best of all, it’s specially formulated to clean quickly without harming paint, clearcoats, and other finishes. Simply spray it on, and wipe surfaces clean.”
For additional information on how to remove bugs and tar from automotive surfaces, Autogeek has a descriptive article.