That song WAS a big hit, and still gets played at weddings (and in this case, it’s actually appropriate for that purpose).
A while back, my brother read a story about it and added that a few years prior to that, he and his wife (yes, the same one) were on vacation and stopped in a karaoke bar, and that song was on the list. And yes, he did sing his own song. 
He sang “Octopus’ Garden” too.
Drummer Debbie Peterson was the lead singer on the Bangles’ popular cover of “Going Down to Liverpool.”
“Help Me, Rhonda” was one of the few #1 hits for the Beach Boys, and it was also one of the few Beach Boys songs that had Al Jardine on lead vocals.
Guitarist Jeff Beck sang lead on the Yardbirds’ “The Nazz Are Blue.”
? Mickey Dolenz was the lead singer for The Monkees. Davy Jones started singing lead on some of the later singles because he was the big girl-crush and because he was willing to go along with the suits when the others were balking. In fact, he sang lead on “A Little Bit You, A Little Bit Me” separate from the rest of the group using session musicians as part of a Don Kirshner power play.
Mike Nesmith usually sang lead on the songs he wrote. Peter Tork got the occasional Ringo-like novelty song. But Mickey was the lead singer from the beginning.
Bassist Jack Bruce and guitarist Eric Clapton split most of the lead vocals on Cream albums 50-50. But drummer Ginger Baker got a rare chance to sing lead on “Blue Condition” from the ***Disraeli Gears ***album.
Trevor Rabin, Chris Squire and Alan White were originally planning to form a power trio called Cinema. They only took back the name Yes after Jon Anderson and Tony Kaye got involved.
She’s My Little Rock n’ Roll by the Stones is Keith Richards singing. I don’t know if it counts as a hit - it certainly got airplay when* Tattoo You* came out.
OK. Hadn’t heard that song for a while.
Don’t forget Sail On Sailor by the Beach Boys. Blondie Chaplin sang it.
Orr sang “Just What I Needed” and “Let’s Go,” but to my ears, he sounds indistinguishable from Ocasek on those recordings.
I’ll just re-iterate what WordMan said: Benjamin Orr could actually sing. He had range and technique that Ocasek, well, just didn’t. Love the Cars, and I actually like Ocasek’s sound. It worked for him. But he had a vocal tone like a nail getting pulled from a board.
Here’s one that might help distinguish the two more. Not saying it’s a vocal tour de force. But Ocasek could not have sung this song.
The primary lead singer for Blue Oyster Cult was Eric Bloom, but both “(Don’t Fear) The Reaper” and “Burning for You” were sung by the guitarist Buck Dharma.
I am totally using that, and will give you a byline. 
Feel free. 
That he did, but his real chance to shine was when he sing-talk-recited-whatever the lyrics to Pressed Rat and Warthog.
A few that come to mind;
“Rock and Roll Dreams Come Through”, the Top 40 single from Jim Steinman’s first and only solo album, was actually sung by session vocalist Rory Dodd. (Steinman lip-synced to it in the music video.)
Pink Floyd’s “Have a Cigar” wasn’t sung by a member of the band at all - it was sung by Roy Harper, who subbed for Roger Waters due to his having thrown out his voice singing “Shine On You Crazy Diamond”.
I didn’t mean my post as a slam against either singer. Both songs were hits pre-MTV when you were limited to just hearing the songs on radio or LP or tape. You didn’t get a visual for who was singing unless you saw them in a concert film or live. The two songs I mentioned in particular I was not aware for many years that anyone but Ocasek sang lead for the Cars. Orr’s style on those two songs was very similar to Ocasek’s on “My Best Friend’s Girl” or “Good Times Roll,” for example.
As not even a casual fan of The Pogues, knowing perhaps 2 songs and the name/face of Shane Macgowan, I never knew that.
I hear the song on most Tuesday mornings, too.
Not sure if it was a big hit, but Long Live Rock was Pete Townsend as lead singer. Keith sang on a few songs but I don’t think any were even close to a hit.
Ric Ocasek agreed with you.
Years ago, when the Cars appeared on the old phone-in radio show*** Rockline***, a caller asked how the band decided who’d sing each song. Ocasek said (only HALF jokingly), “When songs need GOOD vocals, Ben sings them. I sing the rest of them.”