Smart entry issue, questions about engine sound and maintenance interval question

Greetings, it's my first post here. I bought my 2009 Prius about a year ago. The car had ~114000 km on the meter (that's ~70900 miles for the metric system illiterate) and now has 120400. As you can see, I don't drive very long distances. The car has served me well without major issues but a there are a couple of things I'd like to ask about.

The first one is a weird problem with the shotgun side smart entry. It had always been a little lazy, taking a few seconds with my palm in the door handle before anything happened. At some point it stopped responding at all. The driver side and trunk smart entry work just fine. Fast forward to recent days when it has been very rainy and damp. I noticed the driver's side unlocks very quickly at the smallest touch on the handle. Figures, it's wet so conductivity is better. Then I got the idea of trying the passenger side again. It unlocked again. Not as responsively as the driver side but well enough. Seems to me there is some sort of contact issue. Any similar experiences or ideas? Could I try something myself or just take it to a shop? Having it not work is not the end of the world so I'd rather not spend much money on it.

Another thing I have wondered is my Prius' engine sounds noisier than my co-worker's. His car is a 2008 but has about half the kilometers on it. Revving the engine higher is more audible inside the cabin in mine. It does not sound wrong or faulty but it's just louder. Is it just expected as the car ages? Could the engine mounts be worn, causing more vibration?

What's the replacement interval of fuel filters on a Prius? I couldn't find any mention of it by googling. I'm asking because I had an E85 kit installed and wonder if I should have the filter replaced. Even though the car has been running just fine, legend has it that a residue of gunk from petrol could come loose with the ethanol. Just to clarify, the engine noise isn't related to using E85, it was that way before it.

In case you wonder why I would bother with E85 especially when I drive so little, well, because I could (I like tinkering with stuff) and because of political reasons. Also, our local E85 (branded RE85) is made from biowaste which makes a lot more sense to me than growing it on a field and actually has a small cost advantage because of taxation.

 

Thanks for the replies.

What do you mean, exactly? I know E85 has a higher octane rating and benefits from a higher compression ratio so cars specifically designed for it could squeeze more out of it. On the Prius the fuel consumption increase seems to go approx. proportional to the reduction in E85 energy content. It's not a dealbreaker to me, though.

I see. That explains why it's not in the service schedule.