Rotary Hybrid.
 

I've been thinking about this on and off for a little over a year now, and just have to throw this out. Wouldn't a rotary engine mate perfectly with an electric motor? Rotary, high HP with low tourque. Electric motor, high tourque with low HP. With the electric being most powerful at 0 rpm, and the rotary being most powerful up at the top, it seems you would have the broadest possible power curve. Reliability should be good as well. There are very few moving parts in a rotary engine, and even fewer in an electric motor.
The small size of the Rotary engine would alow both to fit in a relatively small engine compartment. According to Honda, their hybrid civic sedan only weighs 287lbs more than their regular sedan. While that is a good amount of weight, it is not much in comparison to the power gains that would come out of it. Now this is a relatively small motor, and battery package, I would imagine a powerful motor and everything needed to go with it shouldn't weight too much more than 5 or 6 hundred pounds.
While this much weight would cripple a nimble sports car, it opens up incredible possibilities elswere in the automotive world. In a truck for instance, you would still get the stump pulling tourque from the electric motor, while getting high HP for plowing and towing. Who wouldn't like to see high fuel mileage from their pickup?
Lets say you put this into an average every day car. Say the Mazda 6. You could get a car that is responsive, fun to drive, and gets fabulous gass mileage. Hybrid cars just don't seem to appeal to the average driver. What does anyone have to gain? It seems you sacrafice the better pleasures of a responsive car for better gass mileage. With this combination, you would gain alot, and lost nothing.
This isn't to say you couldn't put this technology into a sports car / sport oriented car. This however is thinking miles outside the box from where manufacturers have hybrid cars now. Lets say you can engeneir the car so that you can get the maximum power with the least amount of added weight. At 300 lbs, you would lose approximately 3/10ths of a second in the quarter mile. That is with no power gain at all. Now add a powerful Electric motor that if at full power at WOT. Now tripple the tourque at low RPMs and you no longer have to drop the clutch at 8000 rpm to get a decent launch. You don't have to keep the engine over 5000 rpm to be able to rip out of a turn. A power curve that is hight, flat and even is every drivers dream. I would imagine you should be able to put both powerplants in a space about the size of a big V6 or small V8. Battery and fuel placement could create a relatively even weight distribution.
Just my two cents in the matter.

mazda has already doen this. they showed a rotary/electric hybrid several years ago and thena year or so after that had Hydrogen burning rotary/electric hybrid.

ooooold news dude

thanks for the update, after about 4 hours of research I came up with the "Electro-Assist Turbo Hydrogen-Gas RENESIS Hybrid" which is effectively a TURBO RENESIS that runs on both gas and hydrogen. Answers the question on if mazda is working on a turbo RX-8 too.

There isn't a whole lot of info out there, but this seemed to be the best I found
http://rotarynews.com/node/view/458

here's an RX7club.com thread

http://www.rx7club.com/forum/showthread.php?t=368258

Anyone know if our current 8's can be modded down the line for dual Hydrogen/Gasoline use, or it has to be the specific dual use engine that's be experimented on right now??

it's the same engine just a re-maped or different pcm that adjusts for teh differnt fuel (like how a FFV pcm would do it)...also if memory serves it has 2 tanks one for gas one for hydrogen...and you switch between them. so if you can't make it to a hydrogen ffuel station you can run on gas. but it's mpg on hydrogen sucks...but it is a first attempt. so who knows what it'll do if they put some R&D in it :D

So conceivably, any rx8 out on the road today could be modded for dual fuel/hydrogen use?? In case our energy supply changes dramatically down the line :D

By the time hydrogen is readily available, your RX-8 will be a collector's classic in need of complete restoration, and most all the major components will need to be torn out and replaced. So in that sense, yeah any RX-8 is a potential hydrogen car in the future. Along with any '57 chevy.

Actually you probably won't see hydrogen until fuel cells become a practical reality, and once that happens there's no point in using any powerplant besides an electric motor, except maybe for novelty or nostalgia value.