I've been doing a TON of highway travel lately (I'm talking in excess of how far our fuel tank can take us), and I've been using my ScangaugeII Religiously to help me check MPG data.

It shows you realtime, and you can of course reset a 'trip' calculator to show your mpg.

I find that with cruise control active, on average, it gets 19-21mpg on its own, cruising somewhere between 60-70mph.

However, the second I get behind a big truck, and he's at least 4 car lengths infront of me, it goes up a good 1.5mpg easily.

If I get even closer, say two car lengths, (A bit closer than preferred for safety, but doable), The RX-8 sits at 24mpg indefinitely.

I've made long trips with the RX-8, with mostly drafting, and only using cruise control adjustments in 6th grear, and I've gotten 24mpg straight for the whole tank. "decent" fuel economy is possible, if not practical.

I've clocked 320mi on the odometer before having to fill up, and I think that is fantastic. There should be another gallon in the tank at that rate as well, but I'd rather play safe than sorry.

 

That's fine and all, but as soft as the 8s paint is.... I think i'll continue passing huge trucks and eat the gas.

Cool discovery though, makes sense.

 

It was just cool to see an ACTUAL improvement, not some small miniscule unnoticible improvement.

 

drafting is ok, but rubbin is racin ;-)

 

hope you have that fugly nose bra on the car.

 

Trucks spit exhaust and rocks/stones that whack the poor 8's thin paint to heck.

 

you can also draft smaller cars to gain gas mileage

or better yet, run in the middle of a caravan that does 65mpg, guarantee mileage gain!! lol

 

If you'll get just in front of the big truck, you will see an increase in mileage too...as he pushes you!

 

Which means new bumper or repaint in a few months or so.

 

I had my cruse set at 60mph for half a tank and did 206 miles at 7.5gals.....27.5mpg. 04/ AT....its boring in the slow lane....but fun to see what it could do.

 

I get just on 600km (400 mi) out of a tank on highway cruising if I overtake. Wasting an hour to save a dollar is poor economy to me.

 

Drafting increasing your gas mileage definitely makes sense and here is why. Why Mazda or any other car company tests fuel efficiency for a new car it is done in a very controlled environment. This means the car is tested at the absolute best conditions possible for driving which includes negating wind resistance in the factor. This is part of the reason when hybrids first came out they were not getting as good of gas mileage as everyone thought they would. No air resistance = better gas mileage. Putting a giant semi truck in front of you is drafting, which simulates zero air resistance if you are close enough. Truck drivers can be seen doing this with other truck drivers to allow them to driver further without filling up. It is no surprise that drafting increases your gas mileage, but like others have said trucks seem to throw a lot of rocks at my car, which I am not too fond of, but I will admit that I have drafted a truck on occasion on long road trips to help improve gas mileage somewhat.

 

The semis were passing u by furiously.

 

320 out of a single tank, wow. My personal best is 260 with 70% highway driving and I damn near threw a Toga party when I hit that!

 

I get 24mpg on long road trips. Just by setting the cruise control and keeping a steady pace without much passing.

I think most of the improvements in gas mileage that you are seeing are caused by you just staying at one speed and low throttle usage in the flow of traffic as opposed to passing people.

 

I had a conversion van pulling a large "shoebox" trailer when we went karting. 10 MPG. We teamed up with some freinds with a motor home & trailer often drafting them to other tracks. 15 MPG. Keep in mind a conversion van has the wind cD of about .8, and the trailer was a perfect 1.0.

The RX8 is pretty slippery in the wind already. I can see 3-4 MPG as possible but in my case that would come from driving 10 MPH slower....

 

Watch out for road debris when drafting. A discarded tire tread can rip the crap out of the bottom of your car.

 

I have gone 312 miles on a tank, without drafting behind anyone. High altitude flat road, cruise control at 72 MPH, 89 octane Shell.

 

Draft a semi--get ready to get a new front end.

 

I don't get the point of this thread... so you got an extra 1.5 MPG on a trip drafting behind some big truck.

Or an extra 15-20 miles per tank... ohh you almost saved $2.50 (if gas is $3/gal) on a tank of gas.

Wow you could buy a Big Mac or Whopper for hanging out behind a truck...

 

I'd rather let my 8 breathe in fresh cool air, as extended drafting like this on a hot day could be an overheating concern. Personally I stay as far away from large trucks as possible.

 

I dunno what it is with you american guys but just recently, i got 420km (262.5 miles) on half a tank! mostly freeway driving and some city driving?

 

i don't know about your aussie roads, but unless you were rolling downhill the entire time there's no physically possible way you went 260 miles (420km) on half a tank.

 

How? On half a tank per the gauge, of half a tank per 7.95 gallons at fill-up? Either way, you're getting WAY more than anyone else I know of. 33 mpg is unheard of with this car, as far as I know. Anyone care to inform me otherwise on that statement?

 

yeah, I usually draft on the highway too.

-Cody