In west Texas on a trip to California, the oil access cover broke loose and started scraping the pavement beneath the car. The car had 2000 miles left on the standard warranty. I did not worry about it. A local shop removed the damaged component and discarded it. By the time I got to California and returned home, I was beyond standard warranty, but when I bought the extended warranty, I was told it was bumper to bumper. I went to my Toyota dealer. They quoted me several hundred dollars to replace the part. When I asked why my extended warranty did not cover any portion of the part, they said because it was decorative. Before it started dragging the ground, I had never seen the oil access cover. The oil access cover is not decorative.Perhaps it might cut down air turbulence beneath the car, but apparently it is not rugged enough to stand up to wind conditions. No one had ever taken it on or off except the dealer. When the technician assured me that there was nothing critical that the cover protected, I declined to replace it because 1) it was very expensive and 2) I had no reason to believe that a second cover would last longer than the first.

Everything I have been able to find on the net and Prius Blogs say that the mean time to failure of the oil access door hinge on the #1 engine under cover is 4 oil changes. This very poorly engineered plastic hinge fractures in two after being openrd 4 times. I am a Mechanical Engineer. I have worked automotive for over 40 years. I have no idea how a company who is suposed to be the standard that all others strive to be could engineer a plastic hinge that breaks after 4, 90 degree movements down and up. Someone at Toyota has certainly lost face on this one. The original part number was 51410-12101. It has gone through 3. revisions since. Replacement part ends in -12104. This indicates to me that it is still an issue, Refer to: T-SB-0032-11 "Front Edge Of Engine Under Cover Warprd". When this door looses seal, the panel baloons toward the road. At 65mph almost dragging on road due to air accumulation in engine compartment. As soon as the dealer replaces this engine under cover, I am replacing the plastic hinge point with a noncorrosive piano hinge riveted to the fixed and moving pannel. It will be able to brake but the integrity of the pannel is maintained. I dispise poor engineering. This is poor engineering. Shame is upon you Toyota for this. I still like the Prius GenIII. With 100% gasoline, I get 60mpg on hghway doing an average of over 70mph for over 300 miles. Great car, just a screw up by some poor ba_tard in Japan. Poor guy. Needs to know what elastic coefficient is all about. Reality time. The pannel has to be stiff enough to not sag. To try to incorporate a hinge in this pannel using ridged material is not going to work. Toyota needs to put in a mechanical hinge on this door. Enough said.