Mazda RX-8 Gas Mileage Reports

Replying to: KarenS (Jun 02, 2005 10:38 am)

'05 RX-8, bought in Dec '04
 
17 around town
23 highway
11 track
 
My worst "around town" mpg was 15, but that was mostly due to a heavy foot and high revs.
 
Why do people b*tch about the mileage? This is a sports car, not an econ-o-box. Our mileage is similar to other comparable sports cars.

Replies to this message:
• from_fl (May 12, 2006 5:07 am)
  • from_fl (May 12, 2006 5:13 am)
    • trispec (May 12, 2006 12:12 pm)
    • paul_in_dc (May 12, 2006 12:33 pm) and 10 more...
  • paul_in_dc (May 12, 2006 12:32 pm)

Replying to: paul_in_dc (May 12, 2006 4:39 am)

Replies to this message:
• from_fl (May 12, 2006 5:13 am)
  • trispec (May 12, 2006 12:12 pm)
  • paul_in_dc (May 12, 2006 12:33 pm)
    • pathstar1 (May 13, 2006 1:46 pm) and 1 more...
    • geckozoid (Jul 28, 2006 11:23 am) and 7 more...
• paul_in_dc (May 12, 2006 12:32 pm)

Replying to: from_fl (May 12, 2006 5:07 am)

Replies to this message:
• trispec (May 12, 2006 12:12 pm)
• paul_in_dc (May 12, 2006 12:33 pm)
  • pathstar1 (May 13, 2006 1:46 pm)
    • w9cw (Sep 25, 2006 4:06 am)
  • geckozoid (Jul 28, 2006 11:23 am)
    • claires (Jul 28, 2006 1:54 pm)
    • murfbear (Jul 28, 2006 4:44 pm)
    • trispec (Jul 29, 2006 5:34 am) and 4 more...

Replying to: from_fl (May 12, 2006 5:13 am)

Replying to: from_fl (May 12, 2006 5:07 am)

Not a sports car? Ever seen one on the track? Check out the Grand Am series.

Replying to: from_fl (May 12, 2006 5:13 am)

Where in the world do you get 20 years? The Renesis is only a couple years old. Ford has been making piston engines for almost 100 years, yet the Mustang gets worse gas mileage than the RX-8. What's their excuse?

Replies to this message:
• pathstar1 (May 13, 2006 1:46 pm)
  • w9cw (Sep 25, 2006 4:06 am)
• geckozoid (Jul 28, 2006 11:23 am)
  • claires (Jul 28, 2006 1:54 pm)
  • murfbear (Jul 28, 2006 4:44 pm)
  • trispec (Jul 29, 2006 5:34 am)
    • div2 (Aug 02, 2006 9:09 pm) and 3 more...

Replying to: paul_in_dc (May 12, 2006 12:33 pm)

If we talk literally then the renesis is only a few years old. The renesis is based on the earlier rotaries, however. In fact it is very close to the same except for the side exhaust ports (some performance builders are using renesis parts when rebuilding older motors as some of them are improved/lighter - and they fit, just so you see how close the engines are). The earliest rotary car from Mazda that we saw in North America was in 1968, as I recall (the R100). So that would make the engine design at least 38 years old. The basic design hasn't changed much, but the materials have changed a lot - for the better.
 
Early on Mazda tried using side exhaust ports, but in those days the apex seals were very experimental (read unreliable) and needed a lot of oil. This very quickly plugged the side exhaust ports so Mazda had to put the ports on the rotor housing for production vehicles. So the renesis is really not new, just vastly improved over the previous designs.
 
What was improved?
1. Moving the exhaust ports to the side housings allows much better control of the port opening timing, resulting in potentially better mileage and better power.
2. Many moving parts were lightened, raising the redline from 7500 RPM to 9000 RPM (the side exhaust ports also helped with this - when the apex seals traversed the old ports on the rotor housing they "bounced" a lot at high RPM and this eventually resulted in seal breakage). Of course when I say "many parts" I'm talking of only many compared to how many there are - there are very few moving parts in a rotary engine!
3. The PCM (engine computer) is greatly improved, allowing much better control of the engine and providing much better protection for it.
 
So you are both right in some way!

Replies to this message:
• w9cw (Sep 25, 2006 4:06 am)

Replies to this message:
• trispec (Jul 25, 2006 4:55 pm)

Replying to: murfbear (Jul 25, 2006 4:35 pm)