Mazda RX-8 Buyer's Guide

Resurrected Rotary

The rotary engine’s obituary was a bit premature, although American fans had to wait nearly 10 years to see it brought back from the dead. Rather than give up on the dirty, fragile and thirsty engine—the original rotary design was powerful but not entirely perfect for every need—Mazda spent the intervening decade working to improve it.

At the 2001 North American International Auto Show, Mazda revealed the results of those efforts, housed in a neat sports car/sedan hybrid. Engineers basically went back to the drawing board with the engine, rethinking port layout and packaging. It was still a two-rotor, 1.3-liter rotary based on the old 13B-designation engine, but it had changed enough that Mazda dubbed it the Renesis. 

Instead of featuring ports around the circumference of the combustion chamber like all other rotaries, the Renesis’s ports were cut into the side of each chamber. This prevented overlap between intake and exhaust open periods, improving emissions and fuel economy. It also kept the ports away from the troublesome apex seals. 

Before the Renesis engine, rotary designs placed the exhaust port right in the path of the apex seal, and unburned fuel had a tendency to get flung away. Moving the ports to the side of the rotors improved efficiency and performance.

Mazda promised output close to the old RX-7’s Turbo without the need for forced induction. On paper it seemed like an elegant and simple solution to a few of the rotary’s weak spots. 

The display model bearing the new engine was a thinly veiled production version of the RX-8. It was a sports car, but envisioned and packaged in a new way. Compared to the final RX-7, the new car’s roof was higher, and there were two rear-hinged access doors allowing use of the back seat. In place of the RX-7’s cramped two-person quarters was room for four full-sized human beings.

Just as impressive as the new engine and more practical bodywork was the chassis layout. The side-port Renesis was more compact than the old 13B and allowed engineers to move it far back in the chassis, nearly under the dashboard. The stubby carbon driveshaft ran to a limited-slip differential, and the fuel tank was moved up in front of the rear wheels. The payoff was a claimed 50/50-percent weight distribution. 

The RX-8 Debuts

The production RX-8 arrived at American Mazda dealers in the middle of 2003 as a 2004 model. It was nearly identical to the Tokyo Motor Show display car from two years earlier. 

The RX-8 delivered everything the concept promised, as the six-port version of the Renesis engine was rated for 238 horsepower—just a bit shy of the somewhat fragile turbo engine used in the final RX-7. The new mill zinged to a 9000 rpm redline, with peak power coming just 500 rpm before that. This version of the Renesis engine was available only with a six-speed manual transmission.

The Renesis engine is tiny, so it fits low and toward the center mass of the car. Photography Credit: Courtesy Mazda

There was another choice, though. Cars shipped with the available four-speed automatic received a four-port version of the Renesis. The automatic RX-8 produced a still-respectable 197 horsepower at a more pedestrian 7200 rpm.

The suspension of the new car was basically an evolution of the last RX-7, although new tuning and modern tires greatly reduced harshness without giving up any handling prowess. The new suppleness over bumps and the predictable body lean were welcomed by reviewers who were scared off by previous car’s handling and ride quirks. Even the electric power steering was well received for its linear assist and excellent feedback.

Automatic cars were fitted with 16-inch wheels and tires, while six-speed cars had 18-inch tires and wheels. That second combination was good for nearly 0.9g according to contemporary reports. Zero to 60 took a little less than 7 seconds. The RX-8 wasn’t as blindingly fast as the final RX-7, but it didn’t bruise its occupants’ kidneys or require $10,000 in backup funds in case it blew up. Reviewers loved the cars but weren’t sure what to make of the four-door package.

The RX-8’s design is polarizing, but the unusual shape accommodates some genuinely useful rear suicide doors. Photograpy Credit: Courtesy Mazda

Both the automatic and the manual were rated by the EPA at 18 mpg city under their old system, with 25 or 25 mpg highway, respectively. The revised fuel economy figures put the RX-8 at 16/22 mph. Those aren’t particularly impressive numbers for a 1.3-liter engine, hinting that the rotary’s old fuel-efficiency demon had not been exorcised.

The low torque ratings—just 159 lb.-ft. for the six-speed car—also looked weak on paper, but reviewers reported that the engine felt just fine, thank you, as long as the driver was willing to spin it up near its power peak. The RX-8 was a fun ride, but maybe not something for the masses. Enthusiasts took to the RX-8, though, and it quickly became a staple in autocross, endurance racing and track events.

While the manual-transmission RX-8 was not a steal at $25,680, it was still a great performance value. Check every box on the order sheet, and you’d be looking at a total of a little more than $30,000 for the manual or about $32,000 for the automatic. 

Music to Your Ears

Big news for the RX-8 came for the 2009 model year, as the car received a facelift and small but significant design changes. The suspension geometry was revised in the rear, and the chassis was strengthened at the suspension pickup points. Weight decreased slightly as well, improving overall performance.

Photography Credit: Per Schroeder

While the Renesis boasts improvements over preceding rotaries, it has a reputation for not being as reliable as traditional piston engines. Early RX-8s had a number of engine-related problems that were addressed later in production. Mazda USA went so far as to extend warranty coverage to eight years or 100,000 miles for 2004-’08 RX-8s that were already in service. This included repairs that were performed before the new warranty took effect in mid-2008.

Overall, the RX-8 has continued to be the automotive equivalent of indie-label music. It’s different, appeals to many people, and sometimes seems to follow its own direction. The car has enough power to be entertaining and handles better than anything with the same amount of versatility. Today it’s also not terribly expensive to buy.

If you’re willing to overlook a few quirks, the car makes an excellent choice for daily driving, track days and autocrossing. It doesn’t hurt to like the Black Keys, either.

Things to Know

The Mazda RX-8 is still in production. If new is what you want, then head down to your local Mazda dealer and lay down the cash for one. If you want a used one, shop around: We’ve seen prices all over the place. Early cars with blown engines can be found for as little as $5000—or maybe even less—but your average, decent-condition RX-8 will be somewhere in the $12,000-to-$25,000 range; it depends on the year, trim and condition.

We recommend buying the newest one you can find. Mazda-certified preowned cars are nice, but they aren’t a must since the factory engine warranty already extends to 100,000 miles or eight years. And if you have the scratch, the 2009-and-up cars have some suspension and driveline improvements that make them more desirable.

Photography Credit: Courtesy Mazda

Engine and Drivetrain

According to Jim Mederer of Racing Beat, one of the country’s oldest rotary tuners, the RX-8’s Achilles heel is the cooling system: “Mazda has stepped up and extended warranties for this problem, but the engine is still at risk in hot climates.” Jim also reports seeing excessive ignition coil failures—possibly related to high underhood temperatures. 

Thanks to the cooling challenges faced by the Renesis engine, Racing Beat advises against anything that squeezes big power out of the engine, especially turbocharging. 

On a related note, Racing Beat’s PCM reflash lowers the underhood temperature needed to turn on the cooling fans. Jim adds that the reflash also improves the high-rpm mixture and raises the rev limiter to 9300.

“The transmission on the 2004-’08 models is a bit weak for track use, and it may develop shifting issues,” explains Jason Saini, RX-8 racer and owner of Mazda prep shop Team MER. “You will need the transmission and shifter but little else to make this swap,” he explains. The 2009 and later cars also have a slightly more desirable 4.77:1 final drive ratio, he notes.

“Stock class rules allow competitors to modify the exhaust behind the catalytic convertor, and most will use this opportunity to jettison the bulky stock muffler for a much lighter-weight option,” explains Chris Harvey, national-level RX-8 autocrosser and Tire Rack’s brake and suspension brand manager. “Racing Beat offers a very nice bolt-on race muffler for the application, while other competitors choose to design their own custom piece,” he continues. “Coupled with a free-flowing, drop-in air filter, the rotary powerplant emits a proper snarl while negotiating the cones.”

Body and Interior

Jim strongly recommends installing a supplemental water temperature gauge: “The stock gauge stops moving at about 160 Fahrenheit and doesn’t move again until about 205 Fahrenheit, thus making you think the coolant temp is controlled and stable when it isn’t.”

A tip from Chris: If you can stand the aroma, an RX-8 can transport four tires without the need for a trailer.

Chassis

“The bare essentials for track use would be steel-braided brake lines, performance brake pads and high-temp fluid,” Jason explains. “Some sort of suspension upgrade to lower the car would be next on my list, along with track-dedicated wheels and tires.”

Jason recommends steering clear of the budget coil-overs found on today’s online market. “If you can’t afford a good set of quality coil-overs or race dampers, just get some Koni Sport shocks and lowering springs and you’ll be amazed at how well the car handles,” he explains.

The RX-8 features a very adjustable suspension, meaning aftermarket parts aren’t always necessary for an ideal alignment. “On my 2006 model, we were able to obtain 1.8 degrees of negative front camber to increase grip and extend competition tire life using the stock alignment allowances,” Chris explains. He then tweaked the rear toe and camber settings to adjust the steady-state balance, he adds.

“The lightweight four-seater is blessed with 18x8-inch factory wheel sizes that must be retained for SCCA Stock class competition,” Chris explains. “Generous wheel well openings allow competitors to fit wide tires on the wheels without modifications.” He adds that 245mm through 295mm section widths have all been successfully used at national-level autocrosses, “with most competitors settling on the 285/30R18 Hoosier A6 as the tire of choice.”

The front anti-roll bar size has been an area of much debate among the national Solo crowd, with most top-level competitors migrating to a stock or slightly stiffer-than-stock front bar to find the best balance on high-grip surfaces, Chris says. “This choice is contrary to many other Stock-class cars, which require the front anti-roll bar size to resemble a small tree trunk in the battle to control body roll.”