I would pull the pads out and inspect for road grim and debris. Some pads have grooves that can hold small stones. I don’t know about the RAV since I haven’t done a brake job yet. If you’ve driven in mud or deep snow, I would certainly suspect debris.

 

I'm surprised to hear this on a hybrid. Most of the braking is done by the regenerative braking.

Usually brakes aren't covered under warranty work but I believe your case should be an exception.

 

Seeing how you say that you predominantly do highway driving, the perceived scoring may be because of the lack of brake use. The brake surface will naturally get some surface corrosion and you will see some scoring only where the pads make contact. Before talking to the dealer, I would try doing a series of hot stops while only using the hydraulic brake system.

To do so:
1. Find a nice stretch of road, preferably with a hill and no stop signs or lights for several miles.
2. Bring the vehicle up to 50-60 MPH and make sure no one is behind you for a while.
3. As you begin to go downhill, shift the transmission to neutral (this prevents regenerative braking and forces the vehicle to rely on the hydraulic brakes).
4. Firmly apply the brakes nearly to the point that you feel the ABS wanting to kick in.
5. Bring the car down to 5-10 MPH, but DO NOT STOP.
6. Drive the vehicle for 2-3 miles to cool the rotors while avoiding complete stops. Note: Making a complete stop while your rotors are still hot and holding your brakes may result in pad material being deposited onto the hot surface which can cause shimmying later on.
7. Repeat steps 1-6 several times. Once you have done 3-5 of these, make sure you drive the vehicle for a good distance (5-10 miles) on the highway to let the rotors fully cool and before stopping to inspect the rotors.

This should clean up your braking surfaces. Make sure you take before and after pictures so your eyes don’t play tricks on you.

Do all the above at your own risk, be sure you are in control of your vehicle at all times.

A word of warning: These vehicles feel very different when they are relying solely on the hydraulic brakes, especially when burning off corrosion. It will feel almost as if you have about half the braking power as usual, extra pressure on the pedal is required, and you may feel the back end getting a tad “lively”. Be prepared and do not panic; just keep it pointed straight.

 

Our previous four vehicles (not Toyotas) had rear disc brakes and all suffered from premature rear pad and rotor wear. Rear pads lasted about 20K and rotors about 50K while the fronts were trouble free. During the winter in our area a lot of salt and sand is spread on the roads for traction and this flicks up from the front wheels and deposits on rear rotors and acts like sand paper. Also during storage a thin skim of rust will form on rotors and will leave grooves after awhile. Haven't checked our Rav yet but expect it will suffer the same fate. Coincidentally our ten year old Tacoma operates under the same conditions but still has original rear shoes and drums.

 

Thanks for the replies.
I am also surprised and suspect the lack of use combined with debris.
Yes, I am driving in winter conditions same as with my previous 4Runner that didn't exhibit this same early wear (didn't replace those discs until after 400,000 km).
I may try the bedding process suggested by IveBeenRued above after the service visit. I'm not sure it will help though because the feel of the scoring is already significant beyond cleaning up a rough surface.

 

I had problems with my rear rotors and mine was vibrating due to corrosion of salt on the inside (part you can't see). The surface on the inside was very rough but the outside was smooth. Yours might be the same if you live in an area that use lots of salt to melt snow. If you don't grease your slide pins your rotor may wear unevenly also. Perhaps the quality of the rotor may make a big difference. I switched to higher quality rotors with corrosion resistance.

 

Does spraying out the rotors with a garden hose do anything? I do this and around the wheel well. My thought process to wash away anything between the pad and rotor like sand, grit, brake dust, (no salt here).

 

Just an update...
As expected the stealership blew this off as normal wear due to winter conditions. They obviously want to sell brake work. Luckily I am capable and do my own.
(As an aside, don't get sucked into a "free-brake-pads-for-life" sales pitch. The cost of the required yearly brake service versus the "savings" on "free" pads doesn't make economic sense, especially on a hybrid.)
Was time to rotate out my winter wheels so went ahead and took the brakes apart. Upon closer inspection the rotors didn't look as bad as I first thought. Polished them up good with emery cloth. They still have some very minor "normal" grooves but are good. Cleaned up the pads and put it all back together.
Next step is to rebed the pads as described by IveBeenRued. Should be good to go.

 

Another year and another update...
With over 45000 km and another winter the scoring (and noise) on the rear rotors is worse. Decided to pull the plug on them when I did the summer tire changeover. Installed new, hopefully better, rotors and OEM pads.
Depending on how the new one's hold up, I'm thinking about getting the originals cleaned up and use them again in the fall as a winter set.

 

As others have said this is really odd, hybrid brakes usually last about 100,000 miles due to them being hardly every used.

 

Remember that disc brakes are self cleaning but only if you use them. If you are a conservative/gentle driver your hydraulic brakes won’t apply unless you are in reverse or coming down to a stop, below 3 mph or so, which sounds like what you described above. In other words, if you are a really good hybrid driver, congratulations you will get great mileage, but you will have to force the system to use your hydraulic brakes occasionally.

A couple good applications of your hydraulic brakes per week should keep your rotors looking good.

 

...
A couple good applications of your hydraulic brakes per week should keep your rotors looking good.

That's the plan.

 

If you do your own brakes I am sure you are aware of this but for others debris and corrosion can affect the application of equal pressure from the calipers on the rotors. If one of the slides binds up the pads will wear abnormally and much faster. If you take a good look at brakes with this condition the pads will be noticeably thinner on one side than the other. With hybrids the brakes are more susceptible to this condition because they get used so much less (and hence corrode more) so it is a good idea to lubricate the slides annually especially if you live in an are that gets snow and uses salt.