Gas mileage
 

So I started keeping track of my gas mileage due to the short warm up times in the NE heat wave summer we've had.

2 weeks ago I averaged 25.73 MPG on my daily commute. I drive 4 miles to work and 4 miles home, all highway (with a few lights).

This week I averaged 21.32 and I sat in some traffic going to pick something up 30 miles out (mostly highway but some city).

My heat waves have been 95-100 degrees most summer so my warm up times are a minute, 2 minutes tops.

In the winter time with temperaturs below freezing I cant make a tank last me a full week, I get MAYBE 4-5 days before needing a refill due to long warm up's.

I rev the living hell out of my 8 because I know its good for carbon build up "etc.", I have toned it down a bit due to the heat, about 1-3 redlines every time I drive it.

I'm starting to think peoples issues with the 8's gas mileage isn't with the rotary engines efficentcy but with the consumed fuel in warm up time.

And the instance I was talking about over 25mpg, I was 31,609 miles at the previous fill up, and filled up with 8.628 gallons at 831 miles.

Ur lucky! I get on average 15-17. On weeks that I drive it had I get down to 13.

I think the warmup time is killing the MPG average. I think if you started you 8 and drove right away the MPG would increase significantly.

I agree that warmup time skews your average MPG. I typically warm up for five to ten minutes to get the oil temperature as close to coolant temperature as possible. I don't worry about it, my choice. According to fuelly I average 19.9. I have gotten up o 23 on long trips if I can keep the speed under 70, but that's not very often. Speed limit is 75, so I typically run 80 to 85.

I've logged average MPG with my COBB before. If I start after my car is "warm" (coolant needle in the middle), then the calculated mpg will usually be 2 points higher then if I had logged from the start.

Yes, warmup screws the mileage. However, it doesn't screw it much.

Ignition failure, sensor fouling, and compression loss are the primary causes of low mileage in my opinion. I was still getting over 20mpg in the dead of winter with longer warm up times.


Anyone that just whines about not being able to get over 17mpg highway is just ignoring one or more points of failure on their car.

I know i get less than the original gas mileage on this car because i usually don't drive it for long (short trips to home and work specially).

If my 8 gets better than 14MPG I consider that a bad week of driving. We didn't buy the car for the gas mileage. Stop whinning :slap:

As I've said before, gas mileage is a very good indicator of the overall health of your powertrain. For any car, there is a mileage value that you should be able to get if everything is healthy. Whether this is 2.3mpg for a 60,000 ton truck or 97mpg for a series hybrid prototype, or anywhere in between.

Sure, you don't buy an 8 for the mileage, but that doesn't mean that you shouldn't be able to click off 20+mpg highway any time you want. If you can't, something is wrong. If you can, but choose not to, then that is certainly different.

If you have modified your 8 to the point that it can't, and you understand the reasons for that, then you have simply set a different mileage point.

14mpg may be your new mileage point, and if you suddenly only got 7mpg highway cruising, I'd think that it would indicate that something is wrong.

I'm 95% sure my 8 is in 100% (or as close to it as it can be for 32,000 mi.) mechanical condition. I haven't had a compression test since I got it but I'm pretty sure its still really high and I just did plugs coils and wires at 25k and a new battery at 31k

Damn dude, what truck weighs 60,000 tons? maybe you meant train lol. That's one big truck.

Warming the car up like that, is it something that must become routine with every start? Is waiting to hit high rpm until the engine is warm a good alternative?

My S2 gets significantly better gas mileage in hot weather, enough to offset the effect of running the AC constantly. In the winter I'm lucky if I can get above 16mpg, whereas in the summer getting 19-20mpg is easy. The basic problem with small rotary engines is, they leak heat like crazy. On a hot day, the engine bay will heatsoak faster, reducing the overall heat leakage from the engine.

I don't warm up my S2 at all in the winter, so burning gas during warmup is not a factor for me. I just get in and drive.

As I recall, the S1 doesn't have adjustable redline markers on the tachometer like the S2 has, but regardless, the engine computer should still prevent you from revving too high when the engine is cold.

Um, yes, every car needs to be warmed up before you go high RPM and/or full throttle. EVERY car with an internal combustion engine. Most people either don't have a car that fights you if you do, or don't have a mindset that they want to go high RPM or full throttle, so it's largely not taught. A rotary doesn't do well with that, and encourages you to do it generally, so we have to keep warning people to let it warm up. This doesn't mean idle it warm, just take it easy until the fluids are warm.

Yes, the S1 cold rev limit is 5,000rpm(?), the S2 is a 2 stage, 4,000 and 7,000 i think (not sure)