I spent 500 dollars to tune up my prius completely still got 37 mpg at best. My brakes started making that pumping sound that ABSW makes when it is going south. I put it off for the longest knowing it was an expensive fix. I would put my car in park at lights to avoid the pumping sound and possible draw downs on the small battery. $2600 later my ABS system was fixed and they cleaned out a lot of crud from my rear brakes. my Milage jumped to around 44. The mechanic explained that the bogus ABS system was putting I like a partial braking effect drag on my Prius. I am a happy camper.
I drove for almost 2 years with all the ABS and VSC lights on My car would roll down the hill like you'd never believe No drag nothing ever until the last day of the process I had one brake caliper working that was fun changed out the booster accumulator pump accumulator assembly All lights out never look back always was getting about between 44 and 47.1 which was rated at build I think . HV battery failing took er down to 34
It would be hard to respond without connecting with your mechanic and the specifics of your situation, but typically the failure mode where the pump ends up running a lot will not cause brake drag, so for most people there will not be such an effect on MPG when it's fixed.
nason, when you say "they removed a lot of crud from the rear brakes". do you mean that the rear brake cylinder was leaking, and brake dust plus brake fluid built up in the rear brake(s)? That might keep the rear brake shoes from releasing. Exactly what else did they do in your extensive, expensive brake repair job?
