Just purchased a 2005 Prius 63k miles and am learning to drive more efficiently based on members suggestions. I will drive 200 miles at a time twice a week for awhile and was wondering what the optimal speed is for MPG.
Well, to me, highway means 55-65mph roads (2-4 lanes). The most efficient speed is 55 (hard to do though). I have tested nearly every speed and I find my car (an 06) likes 45 mph the best but that's waaaaaayyyyyyyy toooooo painful. I usually set the cruise @ 62 on a 55mph road and 68 on a 65 mph road (as well as on the 70mph freeway). Depending on wind direction and speed, that will usually net me more than 50 mpg's. 55mph will def net you more than 50 mpg's but, 55 is so painful. 68mph nets me between 46 and 48 (usually).
Optimum MPG speed will be the slowest speed you can otherwise accept or tolerate, down to about 15-20 mph. Above that, you will always be trading MPG for travel time, and possibly for safety in the presence of hostile traffic. There are several speed vs MPG graphs posted somewhere around here.
I believe the most efficient speed for MPG for my 05 is 50 mph. It does take some getting use to. Personally I drive 55-60 in a 55 mph zone and get 50 MPG. But my son will drive 50 mph in 55 zone and stay on it in a 45 zone or drop down to 40 to run in EV only before climbing back up to 50 when the ICE kicks on, and starts slowing three times as far back as before. He consistently gets 60 MPG. But last week going country back roads he got his personal best in over 60 miles at 67 MPG by going 40 mph.
^^ I.e. 50 mph cannot be the the most efficient speed when 40 mph is even more fuel efficient. Here is a Gen3 chart, I'm not sure where the Gen2 charts are right now: Updated MPG vs MPH chart
Sorry I didn't define it better. By most efficient I was thinking best combination of MPG / speed / not being a traffic hazard. The least gas use is parked.
As noted above. Real world tests have shown that the true value of the most efficient speed is very low, something like about 20MPH on flat ground if I recall correctly. So in reality your most efficient speed is simply going to be the lowest speed that you can tolerate given your particular roads and driving conditions. Most highway speed limits here are either 100 km/h (62MPH) or 110 km/h (68 MPH). I get noticeably better fuel economy at 100 km/h compared to 110. I generally do about the speed limit, but every now and then I'll go slower and hyper-mile a bit if there's not much traffic.
Thank You for the advice, I am really liking this car just cannot wait for better weather, snowy in Chicago and Michigan
Yeah, its awesome when you first get it. Then you get used to it. Then you drive a different car and can't stand it when it doesn't shut off at a stoplight. It will be so hard for me to drive anything but a Prius now.
One thing that will also help is to not use the AUTO control on the A/C - Heat. When using AUTO the electric A/C compressor will run all of the time. Even though it is electric, it will affect the overall mileage. If you would like to turn off the compressor, simply push the climate button, then tap the A/C button on the MFD. The little line under A/C should disappear showing that the compressor is off. Even though it is electric, the energy used is being generated by either the ICE or regen from coasting and or stopping. I do agree with all of the info above. Our 09 delivers 55+ MPG at speeds of 50 to 55 MPH with the cruise control on flat roads. At 62 MPH, it will usually deliver 50 MPG or slightly higher. Also at 45 MPH, I have noted that it will deliver 60 or better MPG. Your mileage will vary due to temperature, humidity, road types, tires (LRR vs non LRR) and type of fuel along with other factors. It has been suggested to run top tier group fuels. I regularly use Shell 87 octane year round. Chevron 87 is also one of the top tier fuels. I have noted if I use cut rate stations such as RaceWay or RaceTrack that sometimes the Prius MPG seems to be lower. Enjoy the Prius. There are a lots of tips and tricks you can use to optomize your mileage. Top Tier Gasoline Earl Stewart On Cars: How to Maximize Your Prius Fuel Economy - By Rick Kearney http://www.cleanmpg.com/forums/articles/t-pulse-and-glide-plus-warp-stealth-in-the-prius-ii-for-maximum-fe--1224.html
I achieved 52 mpg at speeds of 50-58 leeaving the Chicagoland area on a sunny day temps, 38 degrees. I achieved 50mpg at speeds of 60-65 fairly flat roads, at 70 mph I was at 46-48 mpg. Pretty much what was said by everyone who chimed in. I used to do 80mph in my Vibe awd in the 70 mph zone, now I find doing 65-68 mph is just fine and I relax in the right and center lane, no stress and watch the rearview mirror for all the SUV's going 80 Coming back to Chicago Monday morning from Michigan I drove through rain and experienced lower MPG 48mpg overall versus 50 mpg in sunny dry weather on the same 200 mile trip. I assume this is from the friction of cutting through the rain water on the road, still reaaly goof mileage. My wife could not believe I went 256 miles on 5.1 gallons of gas, I was using 10 gallons in my awd Vibe. Does the engine/battery make a humming noise for awhile after turning off the power? hope this is normal.
Its not the engine or the battery but its the pump that will pump coolant into the coolant recovery tank (aka thermos). The reason for this is to store hot coolant for the next driving cycle to ultimately aid in speeding the next engine warm up cycle.
It sounds like you have a handle on it now, and know what to expect. Concerning the noise, I believe what you are referring to is the pump that pumps hot coolant into the thermos bottle after shut down. You will also hear the same noise upon start up. It is normal, also you may not hear everytime you shut down. The Prius makes all kinds of funny noises, clicks etc. It is unlike any conventional vehicle out there. Good luck to you and enjoy the MPG.
