Losing MPG=If I let my foot of the gas-to coast to stop sign, it feels like the brakes are engaging

Almost certainly not; the brake actuator doesn't generally just start applying the brakes for you.

The feeling "like the brakes are engaging" is probably something else increasing the forward rolling resistance of the car. A matter for investigation.

Of course, if it's at all possible somebody knocked the shifter into B instead of D, that's just what it'll feel like.

 

The OP could drive around for a while and then park and feel near the hub of each wheel. If a brake is dragging (or a bearing has gone horribly wrong, but this would be really rare) one wheel will be much hotter than the others. Worst case the OP may even see a disk or drum glowing from the friction.

Also look under the car and around each wheel to see if something is dragging on the ground or on a tire.

Driving with the emergency brake on would feel something like that too.

 

My experience is Gen 3 so fwiw: if my foot’s right off the gas the car will impose a slight regen drag. You can see it on the display. Touch the gas pedal just slightly dispels it, and the car rolls easier.

 

Have the braking system inspected by someone experienced with this type of work.

Posted via the PriusChat mobile app.

 

I wouldn't have them necessarily limit the inspection to the brake system. That's not the only way a Prius could produce a resistance to forward motion that feels "like the brakes are engaging".

 

Are you in Florida or Vermont at the moment?
If this is something that just suddenly occurred, and the weather is freezing, it's possible your parking brake cable is frozen and not allowing the PB to release. As mentioned earlier, check for abnormally warm/hot rims/brake mechanisms.

 

True enough, but given all of the OP's recent posts, I would start with a complete inspection of the brakes.

Posted via the PriusChat mobile app.

 

If you watch your energy gauge, there is always a bit of regenerative braking when you let off the gas pedal. This is to make the car feel familiar to people who are used to driving a conventional car, and experiencing a bit of engine drag. If you watch your energy flow animation screen, you can see that the gasoline engine is off while you are coasting, therefore it can not provide any engine drag.

 

While the engine is typically off (and not turning) while you are coasting, that's no obstacle to the car using engine braking when it chooses to. All it does then is use the transmission to deliver wheel torque back to the engine, which then naturally turns (though remaining, otherwise, off: no fuel, no spark).

Returning to the OP's issue, there are still a number of possibilities for what might cause the feeling of slowing that the OP is noticing. Checking for warm rotors isn't a bad place to start.

There was a little protocol I worked out for that sort of a test to make it as sensitive as I could.

Given that the OP strongly suspects something about the brakes, that rotor warmth test would be a sensible start.