I'm planning a visit to the Lake Como area at the end of September and I'd like to do some interesting hikes/walks while I'm there. Is a car useful, or just an inconvenience? Can I pick-up some interesting hiking/walking trails using the ferry system, or would a car be better?

Where are you staying? If Bellagio, forget the car.

For any of the lake towns a car is a big inconvenience -

Thinking that having the car IN Lake Como isn't really practical.

We were there in March one time and the ferries were great for getting around as a pedestrian. Even in March there were some auto backups at the ferry. Check about local bus services as well.

We stayed in Menaggio last fall and were very glad that we did have a car, as it gave us much more flexibility than had we had to depend only on the ferries. We took a drive high into the mountains on the western shore one day, drove to a couple of restaurants at night, etc. I am not saying it in necessary but it was certainly not a handicap!

I agree with ekscrunchy. We were in Belagio a couple of weeks ago and the car was very useful for flexibilty of getting around the hillside..and there is plenty of parking. I would warn that driving from Como to Belagio was a bit scary. It was much easier Belagio to Milan.
It really depends on what you plan to do.

Car is not necessary. We are not big hikers and this may be too much info but
#1 there is a funicular that goes from the town of Como up to Brunate. There is supposed to be walk from Brunate to the town of Torno. Supposed to end with a lot of stairs down(100s?)
#2 there is a chair lift from Argegno (200meters) up to the town of Pigra (880 m). Rifugio Buffaloro (1,250M) is up a road or trail.
#3 I have never seen it, but there is supposed to a chair lift from above Lecco up to Rifugio Azzoni (you have to hike from 200 m up to 660M then take the chair lift).
All of these towns have direct boat service.

There are a lot of alpine refugi in the area and some ski-lifts. CAI (Club alpini italia) has a website with some info on the various refugi.

If you want to look at maps then the Touring club of Italy - small scale maps show the Rifugios. Kompass (Germany) sell a nice fold-out map with topo colored on it. Sunflower books (UK) sells a book that covers some walks in the area. There is more. Happy to answer any questions.

I second the recommendation of the Sunflower books.

Car or no car depends on the trails you want to take, but I say relying on the ferries to get around means you always have to be conscious of the time, and you may have to turn back before you've reached your final destination. Also, you'd better take everything you'll need for the day when you leave your hotel (i.e., no leaving extra clothes, etc., in the car).

We did a hike with some locals a few years ago from Menaggio to Breglia where they had left a car. It took about 3 hours. There is another trail from the woods above Breglia to Monte Grona/Grone (can't remember the spelling). The views from the summit are supposedly amazing on a clear day (which we didn't have) -- Como, Milan, Lugano and the Swiss Alps. I don't know how long this second hike takes, and apparently you have to be very confident of the weather before you set off.

There are many trails from Perledo and Bellano which are a few kilometers out of Varenna. From Bellano, the road into the mountains is a nice drive and connects back to the coastal road at Lecco.

Good maps are hard to find. Kompass maps are good, but I haven't found one at the right scale for hiking. Definitely talk with the local tourist offices, your hotel and anyone else you can find to get trail info and conditions. We took hiking boots, but there are trails you could do in sneakers.

I'm with Big Russ. I read the title and thought, "OH, NO! How did THAT happen???"

To fully enjoy Lake Como, a car is not necessary. And what a wonderful thing that is. I've done both. Sometimes I'm in the mood for a car and other times I'm not. I'm not a hiker but I meet many hikers while I'm in the mountains with my camera gear. The hiking trails of Lake Como are famous and every tourist office offers hiking maps. Some of the best vistas are along the hiking trails. For me, a car provides freedom to explore, with or without the camera gear. The best restaurants are up in the mountains. Obviously, you can get to places faster by car and visit many more towns without adhering to a ferry schedule. I was surprised to find, even in high season, parking has never been a problem. And crossing the lake on the car ferry is easy and fun. Many of the hotels offer generous parking choices. I don't think you can go wrong with either decision.

I have seen the car IN Lake Como and the crane lifting it out. A nice black Mercedes. Somebody had a lot of stories to tell after their vacation. Nobody hurt that I know of.

Oh, my, I was just reading another old post where someone put unleaded gas in a diesel car in Europe. It would be fun for someone to start a thread with rental car mishaps. Fortunately, I could add nothing as I've never had any issues with car rental mishaps. (Thank heavens!!!)

Me too...I thought this was a tale of a travel disaster!

so... I'm going to go from the Milan airport to Lake Como and I'm still confused as to whether or not to rent a car or have a driver take us to Lake Como? Sounds like either way is ok but the things that make me unsure about renting a car is that the insurance is expensive and I 've heard the driving is a little scary due to narrow roads and very aggressive drivers. Also, does anyone know if it's easy to pick up your rental car at the airport in Milan and if you don't jave a car, are the schedule of ferries running often? Help , just not sure which is best, car or no car. We want to see Bellagio and Lugano, and who knows what else. Thanks

Context !

Are you arriving at Malpensa? It's an easy drive to lake Como. I know it doesn't make sense to have a car for touring the lake Como area, but renting one was cheaper than the transfer to the hotel, we could park it at hotel, and used it for some trips.
Ferries run fairly often (depends on where you're going). I wouldn't take a car to Bellagio.