Graeme Jones' men were up against it from as early as the fourth minute when Marley Watkins bundled home from close range.
City were worthy winners against a disappointing Hatters side, with Lee Johnson's men even having the luxury of being able to miss a first-half penalty.
The loss saw Luton drop to second bottom in the Sky Bet Championship, with Barnsley edging above them thanks to a 0-0 draw at Swansea City.
Here's how the Luton players rated in the Ashton Gate reverse.

1. James Shea 4.5
Pulled off a decent dive to push away a Josh Brownhill long ranger and then a fine instinctive point-blank stop to prevent Marley Watkins heading a second - must be sick of picking the ball out of the net because his team cant defend crosses | freelance Photo: Liam Smith

2. Ryan Tunnicliffe 3.5
Was largely bypassed in midfield as Town went longer from back to front without any degree of accuracy and was replaced on the hour mark by George Moncur. | freelance Photo: Liam Smith

3. Sonny Bradley 4
Found himself the widest defender for Bristol's 3rd, but was too far away from Weimann who popped it past him to Hunt on the overlap. Was then stranded 10 yards from the full back as he returned the favour to the Austrian | freelance Photo: LIam Smith

4. Luke Berry 4
Picked up a caution for a rugby challenge and then, with the ball at his feet, had so few options to pass to that any efforts often got cut out. But has to be commended to trying to penetrate Citys defensive lines | freelance Photo: Liam Smith