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!