Broke 50 MPG

[nmgolfer]

Thanks for the reply Mark. Your mileage makes sense at those speeds and highway vs. city percentages along with contentious driving. I'm pleased I got 43.8 in combined city highway on my first tank and I aim to do better on the next.

Yes form drag typically begins to exceed rolling resistance (and other linear loses) at about 55 mpg and rises exponentially. That is why aerodynamic form factor (drag coefficient times frontal area or CdA) is so critically important. Unfortunately its not possible to drive 55 in most places and still go with the flow. Jimmy Carter tried (for this reason... and because it saves lives) but Americans like more speed and have longer distances to travel particularly in the West.

Yaris compares pretty good with CdA at 6.13 as compared to 5.84 for the third Gen Prius. But there is room for improvement. I'd like to see more aerodynamic wheel covers and rear wheel well covers on the next Gen Yaris and if they could make it a low cost plug in hybrid with regen braking that would be even better... then we could use racing discs on front wheels and back.

Originally Posted by STC

To start with most of my normal driving routine is highway commutes (country roads) going to the limited city driving at work. I average mid to upper forties.

Occasionally, I take work trips around PA along with my normal driving routine. Trips range from 100 to 300 miles and I have taken two trips on one tank several times. The last three times have all been trips to Hershey, Altoona, and Bloomsburg, PA.

Speed and terrain are the basics for good FE. Using in-gear glides (DFCO) and in-gear glides to minimal braking for city lights furthers good FE. I think one of the most important rules for great FE is to apply the accelerator ever so lightly all the time. When I bought my new car, I drove it like my other cars in the past... jack-rabbit starts and heavy braking to a stop. I got 27-28 MPG! I started to take it easy on the accelerator... and it instantly jumped to the mid-thirties. Then I started with my glides and limited brake use that brought me up to the lower forties. There were other techniques that helped in a minimum amount... duration of A/C & heater, no engine start idling, defroster use, and shutting off the engine at drive-thru tellers, etc.

These last trips involved a decent amount of highway hills (hilly terrain) that I was able to use DFCO: http://www.yarisworld.com/forums/showthread.php?t=4248. Due to the hill lengths, I’m able to maintain my momentum speed for a good amount of time due to the grades. When I’m not able to maintain, I pop the gear into neutral and glide. On ramps and slow downs I used DFCO all the time.

I do not have SCII or Ecometer to check my average speed yet. On the highway I travel the limited speed according to State law (15 MPH below specific speed limit)... Interstate around 40-53 MPH and county roads around 40-45 MPH (once you start to go over 55 MPH wind resistance becomes a factor in the Yaris for FE). City driving is up to the posted speed limit. Whether what gear I’m in, while driving my RPM is mostly under 2,200. When I shift, I’m generally shifting just under 2,000 RPM. When driving in fifth gear or under, I only down-shift when the tachometer drops below 1,300 RPM. While driving on my last three trips most was 2,000 RPM or under. Importantly, with shift points I try to be very light on the accelerator. When there is heavy city traffic, I’m still light on the accelerator, but shift fast through the gears to get up to speed so I don’t piss-off other drivers. I try to learn new driving area environments as quick as possible while maintain hypermiling techniques.

No mods to increase FE. I do have an SS exhaust resonated tip mod that probable has little or no negative affect on FE? My tires are considered low resistance tires (LRR), Bridgestone Potenza RE 92 185 x 60-15. I bumped up my PSI to 42 to help in the roll. My travel is light... my work equipment and luggage is around 70lbs. The fuel I use is RBOB gas (non-ethanol)... approximately 1-3 MPG better than ethanol gas. Soon the gas will be leaving this area and I will be forced to use ethanol gas additive.

Does this specific information help?

Cheers!

[STC]

Originally Posted by nmgolfer

Thanks for the reply Mark. Your mileage makes sense at those speeds and highway vs. city percentages along with contentious driving. I'm pleased I got 43.8 in combined city highway on my first tank and I aim to do better on the next.

Yes form drag typically begins to exceed rolling resistance (and other linear loses) at about 55 mpg and rises exponentially. That is why aerodynamic form factor (drag coefficient times frontal area or CdA) is so critically important. Unfortunately its not possible to drive 55 in most places and still go with the flow. Jimmy Carter tried (for this reason... and because it saves lives) but Americans like more speed and have longer distances to travel particularly in the West.

Yaris compares pretty good with CdA at 6.13 as compared to 5.84 for the third Gen Prius. But there is room for improvement. I'd like to see more aerodynamic wheel covers and rear wheel well covers on the next Gen Yaris and if they could make it a low cost plug in hybrid with regen braking that would be even better... then we could use racing discs on front wheels and back.

You’re welcome! 43.8 MPG combined on your first tank is very good. More likely you will do better the next time around. With that first tank, what was your percentage in city vs highway driving and speed? How about terrain? Years back when I was in Albuquerque, New Mexico, I recall on the Interstate some long grades, but not much steepness?

Yes, CdA is non-linear in scale! That is why I keep my speed under 55 MPH. Honda in my eyes has always made cars with good CdA design in mind. Too bad they stopped making the CRX line in the 90’s.... they were great non-hybrid FE cars. What’s up with Honda today? Their 1st Gen Insight was great in CdA numbers!

I’m fortunate that I can drive under 55 MPH. The flow seems like 55-60 in posted 55 MPH zones and 65-75 in 65 MPH zones. People don’t pass me going terribly fast. I’ve gotten a few beeps (3 so far) and a couple of fingers... LOL! Most importantly, I’m not a hazard to others driving safety. We have large Amish communities in Central and Southeast Pennsylvania... most people drive carefully on country roads because of the hills and slow moving Amish buggies.

That was actually a wonderful idea that Mr. Carter thought up of during the second gas crunch in the 70’s. Too bad, it never became very popular. Could you imagine if everyone drove 55 and under with basic hypermiling techniques? ...Less deaths, personal vehicle expenses, and of course less oil consumption.

Let us know how your FE does in future tanks, Rick!

BTW: Contentious driving? I'm more of a conscious driver. I’m passive when it comes down to driving...

Cheers!

[bkrownd]

Originally Posted by STC

I’ve gotten a few beeps (3 so far) and a couple of fingers... LOL!

What a bunch of selfish morons. Glad I don't live in road-rage country anymore! People are perfectly happy to go a sensible 45-50 here.

[STC]

Originally Posted by bkrownd

What a bunch of selfish morons. Glad I don't live in road-rage country anymore! People are perfectly happy to go a sensible 45-50 here.

Well, the drivers in my area are actually mellow drivers. It was on my trips to eastern PA and the big cities that I got those welcome responses...

[docB]

What kills on the highway is the difference in speed. Also, todays and the Carter era cars were designed to run best about 60-70 mph. 55 usually has a rhythme with the road that puts you to sleep. Todays stats show more people on the road driving a bit faster w/ less carnage.

I run 42 in the front tires, 35 rear. Less understeer. 15" Goodyears. The RE-92 is a mileage tire? With a tread rating of 160, that is not the case.

I also have a hard time with instantaneous FE figures. Track all the gas you burn and give me the milage from that. I have over 11k miles and am just shy of 40 mpg for allof them.
doc

[STC]

Originally Posted by docB

I run 42 in the front tires, 35 rear. Less understeer. 15" Goodyears. The RE-92 is a mileage tire? With a tread rating of 160, that is not the case.

Actually, the Bridgestone Potenza RE92 165/65/14 and RE92 175/65/14 are LRR tires. The 185/60/15 is considered a LRR tire, but does not have a stamp to show. So, they are probably not? At least this is what I gather?

I also have a hard time with instantaneous FE figures. Track all the gas you burn and give me the milage from that. I have over 11k miles and am just shy of 40 mpg for allof them.
doc

Actually, these are not instantaneous figures. I track all my gas mileage from pump 'click' to pump 'click' and prior write down all the 'bar' drop 1/8 increments. On the tank when I fill up is usually on the 7th bar or the last bar (single flash). I add the total mileage once the pump 'clicks' and write down the amount of gallons on the pump. I always use the same pump. I have no Scanguage or Ecometer yet... so I can't use instantaneous figures. These are real life figures...

I had three consecutive 50+ MPG on the tank during the mid summer. I knew to make four in a row would be difficult since my driving would not involve taking any trips. I was correct. I was just short of 50... 49.349 MPG to be precise.

Cheers!

Gas Tank mile increments (non-ethanol gas used):
1st Bar drop (8/8) > 93 mi (93)
2nd Bar drop (7/8) > 78 mi (171)
3rd Bar drop (3/4) > 64 mi (235)
4th Bar drop (5/8) > 55 mi (290)
5th Bar drop (1/2) > 80 mi (370)
6th Bar drop (3/8) > 58 mi (428)
7th Bar drop (1/4) > 63 mi (491)
8th Bar drop (1/8) > 02 mi (493)

Tank total : 493 miles
Fuel used: 9.990 gallons
MPG: 49.349