Fuel Economy on 17's

17's on mine as well. Ive only put a couple tanks through but look to be getting 50-51mpg each time.
Im in the Pacific NW and flat roads are rare so I'm pretty happy with it!
Hopefully it will get even better as I learn the car more.

 

Only if I use the A/C. If not then mpg is great due to lower rolling resistance. A/C is what kills mpg in hot temps.

 

I am doing just fine with 17" wheels and Primacy MXM4's at 46/44 psi. Calculated FE on a recent (previous tank) hyper-miled tank (630.9 miles) was 56.5 mpg. Just filled up tonight after a couple of weeks of more pleasurable (i.e., aggressive driving) and calculated mpg was 53.6. I can live with that number given my liberal use of power mode and zippiness in traffic.

And this more aggressive driving tank was waaaay more fun and less stressful than the previous hyper-miling tank. Don't get me wrong, I will still try for the 700 mile club in the fall or next spring, but don't see myself routinely going to hyper-miling mode at every conceivable opportunity. A bit too stressful with some of the other cars on the road.

 

Are your 17" wheels quite a bit lighter than the OEM 17" wheels on my car? I have a feeling that would go a ways toward improving fuel economy.

 

Agree with F8L --- mpg takes a hit with a/c use. I have been able to lessen the hit by switching to eco mode, but then the engine power performance takes a hit. When it is about 100 F then 80 - 84F in the car is not too bad. I grew up in AZ and am acclimated to higher temps.

 

Don't know for sure but the Momo Win2's felt pretty close in weight to the OEM 17's when I compared them at the shop. Pehaps F8L or someone can comment on the actual weight differences.

 

Wheel weight doesn't seem to play a huge role in fuel efficiency. If it did, Toyota would not have chosen wheels carved from lead! Seriously, I had lightweight 17s (15lbs/ea.) and the mpg loss seemed on par with the stock wheels at 24lbs/ea..

Other members have purchased lightweight 15" wheels and noticed no difference in fuel economy. My guess is that there is a gain associated with lighter wheels but the numbers are so small that they are hard to realize in normal day to day driving. Thus I would focus on getting the correct offset to minimize airflow disturbance and get a good tire. If you can afford a lighter wheel then go for it but don't break the bank to do so. AZGeek's setup is a good example of what can be done for a budget. It looks great and performs admirably.

I'd like to see someone try the Bridgestone Turanza Serenity Plus tires.

 

My guess is that, all other things being equal, heavier wheels are going to be a hindrance to FE in stop-start driving and a slight help in highway -- angular momentum being the only real factor, and a small one at that.

I'll certainly take a look at the new Turanza's. I like the 215 footprint, but 205 isn't too big of a loss, and the extra tire height should give a bit more comfortable ride.

 

Spot on. I get better numbers in the morning since I do not use A/C. Afternoon the A/C is required...we average 102F.

 

I'm wondering if anyone has kept data to see at what speed the drag from open windows counters the increased power demand from the A/C. For me, it "feels" like it is right around 40-45 mph, but I have no real data to support it. I DO know that at highway speeds open windows have a greater negative impact on MPGs than the A/C. Also, use of the Eco mode makes the A/C less of an efficiency loss.

 

Still on the original tires. The last 3 tanks were 59.5mpg, 59.0mpg & 59.4mpg (1670 total miles). I don't think I'll make 4 in a row as I'm showing 60.4mpg with 2 pips left on this tank. The lifetime (since December 2009) is in the sig.

 

I've tried this experiment and I always suffers larger hit from A/C. Maybe after 30min of running the A/C and the car has cooled down the hit will be less but in my experience it takes a long time for the A/C to stop pulling more than 600w when it is 95F+ outside. Rolling down my driver's side window fully and cracking the rear passenger window does not create an identifiable drop in mpg. I regularly try to test this idea when traveling on smooth rural roads at 55-60mph and I cannot separate a true change in mpg from the noise (road surface and elevation changes) on my Scangauge. The second I turn on the A/C my mpg will drop between 7 and 10mpg for at least 10min until I turn it off or the cabin cools down. 1800w power draw sucks! Literally. LOL

 

^ I've heard there's less of a hit if you set the A/C temperature fairly high when first starting it, to the point that the fan speed drops to around medium, then gradually lower the temperature, staying above the temp. that causes the fan to race.

 

When the interior of the car is 95F+ you can't set the temp high enough to keep the fan from racing. I've even tried lowering the fan setting but it doesnt seem to help. I have not tried that technique extensively, however.

 

Thanks, F8L! I wonder why I haven't experienced quite the same extreme difference. Of course, I haven't subjected my observations to real scrutiny or any repeatable tests.

Have you tried it with more windows down?

Thinking about it a bit more, my typical practice is to drop the windows and drive for a short while before turning on the air. This drops the interior heat quite a bit before the fan starts. Any help?

 

I've tried it with both front windows down and the rear passanger side cracked and still couldn't tell a difference in mpg. I'm almost certain there is an effect but it appears to be quite low at speeds of 55mph or even 60mph. I've not tested it above this speed, however.

I suggest rolling the windows down when first entering the car and driving for a little while before turning on the A/C. It takes a few miles for the car to warm up and the A/C to really start working and data suggests the cooling effect is basically the same u til the A/C is ready to run full bore. Keeping the car interior as cool as possible while parked should be your first priority. Remember that your HV battery has to sit in that baking heat all day. It cant be good for longevity. A heat soaked interior is not good for you, the battery or your fuel economy.

How to Reduce MPG loss Because of A/C Use | PriusChat

 

Go for it!

 

My current tank is only a little above 500 miles right now. I just dropped to one "pip" and certainly have many more miles to go, but I'll be filling the tank Friday, regardless. I leave early Saturday on a road trip, and I definitely do not have enough has to take the risk of heading out into the country without gas in the tank! The first half of the tank was showing MPGs right at 60 MPG, but that involved several days of longer distance, though local, driving. The past couple of weeks has been very short trips, mainly with A/C on, so I've dropped the current take to only a little bit above 57 MPG. The past 800 miles has been just local driving, with my average speed at 21 mph, and the MPGs show 56.6.

I have a feeling all of this will change shortly as I put new shoes on the car. My Toyos are getting a bit thin!