I love the looks of the Rx8 and the hidden doors, I wish they could work that into a Ford. But the deal breaker is power. What are you gonna do the first time some Civic runs you down, those imports are hard to slide down under the wheel.
For the more broad-minded car enthusiast, a Mustang/RX-8 comparison is quite reasonable -- that's one I'm mulling over. They are both, broadly, front engine, RWD 2+2 sport coupes of roughly similar size. Aside from that, each has is distinctions.
I too have driven the RX-8 and found it to be a fantastic little car. The suspension/steering/braking are all simply superb. For anyone who wonders what a good IRS can do for both ride AND handling, they ought to take a spin in one of these over a long winding and bumpy road, one that would stagger a live-axle Mustang to a hammering crawl. The rotary motor is quite a technically facinating piece, one with power characteristics diametrically opposed to that of a big-cube, low-rev V8. Yes, it isn't as quick as a Mustang, particularly at low revs. On the other hand, boy, does it simply love to rev though and thus, is a real joy to spin up to 9K through all six gears -- a fantastic shifter and light, communicative clutch help here too. Again, while not as fast as a Stang in a straight line, it's by no means a dog either and by dint of its superb suspension, can probably use a far greater proportion of its available power over a much wider range of roads than can a live-axle Stang. The interior is very good, though the window beltline is a bit high as seems to be the fashion these days for some reason (fails the elbow on the window sill cruise'n test). The suicide doors are quite clever and effective in making the back seat actually accessible to more than limber circus monkies. Styling, while obviously a personal thing, is at least original, interesting and not formulaic.
As for the '05, said without the benefit of any driving reports, should be worlds better than the current dinosaur. While the Mustang's V8 oomph is undeniably fantastic, along with the heavy-metal thunder, everything else quickly falls to adequate, acceptable to just plain bad, be it the terrible interior ergonomics and quality, the dead steering or the lively axle that is immediately brought to its knees on anything but the creamiest of road surfaces. The '05 looks to right much of this and add even a bit more steam in the engine room. The ox-cart axle, while it will undeniably be an improvement over the current contraption trussing up the derriere of the current car, is still a bit of a disappointment on a 21st century performance car, regardless of what focus-groups the design team is trying to hide behind in justifying this engineering anachronism (tradition, well then, where are the drum brakes and leaf springs?).
In any case, I'm waiting till I get some tire to tarmac driving reports on the '05 before making any decision to part with some greenbacks. And yes, the RX-8 is way up on the candidates list along with the GTO, EVO, STi among others. All these car's do/should be excellent choices and much will come down to individuals preferences and wants. If you're primarily a straight-line maven who sees performance but a 1/4-mile at a time, then the Mustang's attributes might be more in your camp. If, on the other hand, like myself, you give equal weighting to the other 359 degrees of the performance envelope, then the choice becomes more complex and might require a bit more wheel time to make a final decision.
I gotta say the more I see RX-8's the more I really like their styling, from all angles. Haven't driven one yet but my friend who's in the market did, he said it's pretty slow. I think they have a new RX-7 coming out, might wanna wait for that, or a more powerful 350Z.