Robotto Keiji, or Robot Detective, was a tokusatsu series that ran from April 5 to September 27, 1973 for 26 episodes.
It was created by the legendary Shotaro Ishinomori, the man behind Super Sentai, Kamen Rider, and many others.
A scientist builds a robot detective with a human personality to combat a group of murderous robots created and led by her crazed brother. Robotto Keiji K (or Robot Detective K) has no human form, so when not in battle, he dresses in human clothes to blend in. His car seems to resemble one of those ambulances from the '70s but modified to break the sound barrier.
Here's the theme song: