Some Observations On MPG

I'm also finding 3rd Gen Prius CC delivers very good efficiency, at steady speeds. Where you can still beat it easily is in stop/start conditions, where you can opt to coast to your next slow down. Especially if there is no one impatient behind you, you can be strategic with your speed, just taking adavantage of momentum, coasting.

 

wow, cc on surface streets. that would never have occured to me. what speeds are you talking?

 

Strange. Most hyper-milers would say that the cruise control is not the best way to maximize MPG. But, if it works for you go with it!

 

If the first tank reflects dealership driven miles, then almost anything done during the second tank will appear to be an improvement.

Selecting the ECO mode gives a more manageable throttle for P&G but if you're driving at a constant 45-50mph there is a better method.

 

The 3rd Gen is a little more finicky when it comes to pulse and glide which is why some prefer the GenII. If you don't have the technique mastered then it can actually hurt your MPG so my advice is to not bother trying to pulse and glide until you have a lot more miles under your belt.

At higher speeds you can try out Super Highway Mode and other techniques but like I said, wait until you have accumulated more driving time so you can learn how the car works.

 

I use CC a lot, but only on freeways. I try to pulse and glide whenever I can on surface streets, and on freeways when traffic precludes using CC. I have even seen the car in glide mode and CC at the same time, although it is rare and doesn't last long. Go with what is comfortable for you, and your mileage will probably improve as both the car and you get "broken in." Warmer weather will also help your mpg.

 

7 mile commute is a fairly short commute so your Prius' fuel efficiency will drop signficantly in the winter time because of warmup cost. Cruise control(cc) should work better than a normal (extended) Pulse and Glide (P&G) because its more likely to keep your engine running longer for the first few minutes and thus more quickly warming up your Prius to its most fuel efficient operating temperature than an normal P&G cycle. It is only when your engine warms up (to about 140F and then to 180F ) that it will run efficiently and benefit from an extended P&G cycle. When starting from a cold start on a dry but cold (<40) day, the Prius needs to be running for about 15-30 minutes before its FE can fully benefit from an extended P&G cycle.

Unfortunately, with your 7 mile commute, this means that the benefits of the P&G cycle can only been achieved in the latter half of your commute.

Because your commute is short you must focus on warming up your gasoline engine (aka internal combustion engine or ICE) for the first 4 minutes of driving. This means avoiding using electrical power ( left side of the ECO bar on the HSI) and use the ICE instead (right side of the ECO bar on the HSI). When not using an engine block heater or some external heating system, hypermilers use a thing call mini warmup P&G cycles. This means from a cold start pulsing the the ICE to 10 mph using the ICE only for the first minute (by pressing the accelerator over the 50% (half way) marker on the ECO bar on the HSI display then letting go the accelerator so that the HSI display is on the very far left of the ECO bar but not in the recharge bar section -so that the Prius glides at 10 mph for a short time just on momentum using very little electric power). When the Prius speed drops to about 5 to 7 mph accelerate further, incrementally increase the top speed of the next pulse to about 15 to 20 mph, repeating this process again but allowing your glide to drop down only to 10 mph to 15 mph before pulsing again. On the next pulse raise your top speed incrementally to about 20 to 25 mph, repeating this process again but not allowing your glide speed to drop lower than the previous pulse top speed. Do this repeatedly until you get to your desired speed. Min/warmup P&G can be difficult to do.

If you are going on a superhighway setting CC is the easiest way to limit your speed to under 65 mph and get the best fuel efficiency. On the superhighway the prius CC can get about 64 mpg when fully warmed up and driving constantly for hours between 50 mph to 55 mph.

If you are going on suburban-urban roads then timing your Prius with the traffic lights so it doesnt need to stop at the intersection is your best tactic. In hypermiling lingo = driving without brakes aka DWL. The Prius can achieve an instantaneous MPG between 60 to 80 mpg using P&G at speeds from 15 mph to 30 mph when combined with DWL.

On fairly long sections of suburban roads when traffic permits it, the Prius FE is best when driving from 25 mph to 35 mph. With a fully warmed up ICE, P&G between 25mph to 35mph can achieve an instantaneous mpg of about 60 mpg to 70 mpg.

In stop-n-go urban traffic that last longer than 10 minutes, its best to avoid using Electric power (to avoid depleting the HV battery power) and do min-P&Gs to inch along in traffic. MPG can drop as low as 15 mpg if you deplete your HV battery during a traffic jam. On short trips less than 3 miles/3 minutes the Prius gets between 15 mpg to 20 mpg.

hope this helps

Walter Lee
'HyperDrive 1" on cleanmpg.com
2010 Toyota Prius III, Blue Ribbon/Dark Grey. oem floormats
Yokohama Avid S33D
ScangaugeII
grill blocking
odeometer 17700 miles, overall mpg = 60.9 mpg