Actually, the EPA numbers DO tell the story. The telling part is the highway cycle mileage, where the TCH advantage is primarily from the more efficient ICE. In that case, the advantage is roughly 10%. The city cycle advantage is from the combination of ICE shut-off and the not throwing away the energy in the momentum in the form of brake heat (regenerative braking). Other advantages inherent in the TCH design include the elimination of the stepped auto trans and the fluid coupling (torque converter). This is one factor that gives big boost on the city cycle, as lock-up in the conventional automatic doesn't happen while accelerating.

The sum of these advantages is what's responsible for the 57% boost in the city cycle of the TCH vs the "regular" 4 cylinder Camry. Given consistent driving styles (e.g. "hypermiling"), the advantage would hold up. For all its criticism and the 'lack of correspondence to reality', the EPA cycle does give decent relative ratios that do hold up. Now, some drivetrains may be more optimized to the test cycles than others, and might 'break' the ratios, but that's another day's discussion.

It holds up. I ran the numbers from my earlier post and got 46% over the 4 cylinder Camry. The difference between the 46 and 57 can easily be rationalized by the rural highway content where the "city" advantage is lost.

It is the ignorant among us that will eventually destroy us all.

The following observations apply to my driving with no extraordinary technique save limiting my highway speed to 65 miles per hour max.
Seeing that I own both a 2007 TCH and XLE-V6 I will offer the following...
Without special driving techniques the TCH beats the XLE-V6 in city driving by a margin of 2:1. However on the highway I limit my max speed to 65 miles per hour and the XLE-V6 gets close to 35 mpg on flatland and maybe 30 mpg in modest hills compared to the TCH getting about the same at 65 miles per hour. With the larger trunk of the XLE it has become my road machine of choice. It's added power/passing ability is an added benefit as well.
If the only driving you do is highway I would suggest you at least consider going with the non-hybrid for the same $$ and enjoy it's better highway driving abilities. BUT if you do any amount of city driving it's hard to match the TCH. The V6 sucks gas when sitting at stop and go lights and if you turn the engine off at every light (as the TCH does) I think you'd probably be replacing the starter rather quickly.

I think the "real" advantage in terms of mileage is going to vary for each person based on a number of factors that have been discussed on here numerous times and i won't bother listing them again. On average i imagine the normal Camry would get 24-28mpg for the
4 cyl model, that is. In the TCH my average is hovering around 38-42mpg for the year that i have owned it using no extreme hypermiling techniques.

My 2000 Subaru Outback (4 cyl.-2.5L - they didn't make the V6 back then) would only yield about 650-700km/65L tank of gas - MAX. - with every trick (shifting to neutral, etc.), this is the best I could get out of a purely ICE car. The Sub. was made in Indiana - the 2009 TCH is/was made in Kentucky. So, after 8 years and 400,000km on the Sub., I decided to sell it, and purchase the '09 TCH.

I average, without trying too hard, about 900-1000km on the same 65L tank of gas. When you compute the L/100km (mpg) and the rising cost of gas, then it should be fairly clear which car is the better buy in the end.

No one ever asked me how my Subaru performed in terms of FE (only the AWD in snow), and now, almost daily, I am CONSTANTLY answering questions like, "How do you like the hybrid?" and "What are you getting out of a tank of gas?"- not sure if I like all the extra attention...Still very ecstatic about the car - or I wouldn't be posting here now...