Just bought a new 2012 Camry Hybrid LE 2 weeks ago. Been obsessed with watching my driving habits and how it affects whether or not I'm using EV mode only.
I've gotten it down to the point where I can make 4 stops on the way to take my son to daycare and can use very little gas actually "stepping on it" to get get going.
The best I've done so far is 72mpg for the 4 mile one way trip. 64mpg another time, and about average is 55-57mpg.

What I've noticed, is that I drain the HV battery before I can get home, forcing the gas engine to kick in(even though I don't want it to).
Which means I'm not coasting/braking enough to charge up OR my HV battery doesn't have enough capacitance for my 4 mile one way trip.

Short of further refining my driving habits to perfection, Is there anything out there, OEM or after market, like an add-on battery pack or capacitor bank that will add to my overall battery storage to allow me to travel further on just battery?

 

No reason to worry with the traction battery. It's fine as it is, just refine your driving habits. It took me 5 years with my '07 TCH to learn as I went. Although the first year was were I learned most. You can drive the car at 37 mph with cruise, then not even worry when the engine or EV is propelling the car. I have found at 37 the car knows when to EV and when not too.

The slower you go the more the EV will be used and the 'farther it will go'. Easy takeoffs when possible staying in EV will up your mpg. That works best with a near full charged battery. Anytime the battery reaches down to about 15% the engine will start to recharge the battery which usually takes a mile or two.

I use the Michelin primacy LRR 'green-X' tires with 44 psi cold in them. These are the same as the oem tires (93V) for the XLE hybrid. These particular tires shows a 51 psi max pressure on the sidewall. Your LE TCH may have come with the Michelin Fuel Saver tires which is as good a LRR tire as I have on my car. If you air them to 40 psi to improve mpg, best if they are Michelin's. Be sure to check your sidewall for your tire's max pressure. Caution if your caps on your tires are green they may have nitrogen in them. If so let the toyota dealer up them for you. Some though near refuse to go above the factory recommended pressure. That's for a great ride when testing driving the car.

If you ever been to the white sands national monument you know about the rather level highways, dry climate and little wind which helps some with my mpg. It's 4200 feet elevation here and the slightly thinner air helps due to less air resistance on the front of the car. I can tell this by coasting a short ways in neutral. Remember when any coasting your on manual brakes. The regen and power assist brakes only work when in drive.

I'm at a half tank so far using phillips 66 regular gas. I would recommend you to use any top tier gas from the www.toptiergas.com/ site. Play the video first, then click the Retailer link to see the list.

My car is very new now and is around 3500 miles now. I will stick with the 0W-20 synthetic oil when I change at 5000 miles. I use mobil one oil as its reasonable priced and easy to buy at walmart. At wally I take the oil to the auto counter for them to change it. I prefer to use the oem filter from our local toyota dealer. I place the filter in the front car seat so the auto tech can use it.

My personal record on my '12 TCH tank is 815 miles. I'm working to improve but not sure how this one will come out. The 815 tank was at 57 mpg and this one is nearing 61 mpg. Evidently my car is near broke in. Near all my driving is on a repeated near daily 33 mile round trip to town and back home. We live 8 miles south of alamogordo near the el paso highway. So I know ever spot where the EV should start and some where I can pull my cruise level down once or twice and the car will drop into EV. I have lately learned with a full 80% charge I can run in EV 1 or 2 miles going up a slight grade while driving a way from a small bridge. Here below is a picture I took last night. The green you see is a scan gauge II I use at times to help me improve my mpg. You can do near the same by using the new ECO meter on the '12 TCH. Try keeping your needle anywhere below the ECO 'text' in the ECO meter. Try various speeds, best if you can stay at 40 with cruise or better around 37, depending on traffic and if your in a safe area to drive that slow. Gradual braking helps to recharge the battery faster.

I may repeat myself but this half tank is by driving at 40/37 and 30 mph, 25 on the 2 mile road to the house. I always use the cruise.

The .04 GPH you see, should have read .00 which was a pgm bug in the early Scan Gauge II units.

HalfTankRecordSept2012002.jpg

 

Not sure if this is for the Gen1,2 or both but an add on battery pack will be "available soon" from these guys.

http://www.pluginsupply.com/pricing/

If you wanna' play, you gotta' pay!

Or you could just trade in your new TCH for a PIP (plug-in prius), or Leaf, or Volt or......

 

Trust me, buying gas is much cheaper. They are a some that buy used or rebuilt traction batteries and piggy back them and get a big jump in gas mileage. Then their's the added weight of the extra pack, maybe 160 pounds which isn't that bad. I'm not sure if the second pack charges from the car or a external charger when at home.

 

The first thing you have to consider is that all the energy you use in a Camry Hybrid comes from the gasoline fueled engine. The gasoline engine has to run to provide all the energy, no matter how many games you play with the way you drive it. You either use the energy directly from the gasoline engine, which is the most efficient, or indirectly by electricity from the battery.

The electricity stored in the battery comes from two sources. One is the motor generator using gasoline energy to charge up the batter, and that requires the gasoline engine running. The other is to use kinetic energy from the car when you are slowing down (regenerative braking) to charge up the battery. Either way the root source of energy is the gasoline engine.

The second thing to consider is that there are losses in the inverter circuit which converts power to DC to charge the battery, and then reverses it back to AC to power the electric motor. Even the electric motor is only about 90% efficient. Short story is that EV power is relatively inefficient compared to gasoline power when the gasoline engine is running at maximum efficiency.

If you want to maximize fuel economy you should focus on making the gasoline engine run at maximum efficiency. And, probably the best way to do that is to let the automatic control system start and stop the gasoline engine, and try not to second guess it. And, second you should try to make your regenerative braking as efficient as possible. Do not over brake and waste energy in your disk brakes. Do not use the B mode of the "gear selection", unless your battery is fully charged and you are still going too fast down a hill.

So, no you cannot increase fuel efficiency by buying a larger battery or capacitor.

 

I have a feeling we may be seeing the ultra-capacitors in the hybrids hopefully in the next 5 years. Large capacitors charge rather quick, can be drained fast or slow.