Worse consumption when driving long distances

So many factors could affect it. There is a sticky on here that asks you to complete details of your car that could explain the lower mpg, otherwise it's all speculation.

I drove a 400 mile round trip at about 85 mph including a couple hours in central London and still got mid 50's to the UK gallon (45 US).

To get 29 mpg you must have been either hammering it or driving up hills. But without the completed details in the sticky, it's speculation.

Welcome to the forum.

 

Are you SURE you were going downhill?

The angle of the road can be deceiving, and you might have been going up a very gradual uphill grade, but the surroundings made it look otherwise.

Without a GPS telling you your current elevation as you travel, you can't be certain which was the case.

 

We have a strange road like that near me. It really is weird to drive along.

 

welcome to priuschat! how long have you owned her? how many miles on her? what was the battery meter doing during all this? what kind of elevation changes are we talking about? sounds like some serious mountains.

 

Welcome to Prius Chat! I too second what bisco said above. You also need to provide more information about the topography of the roads you were driving on. FWIW, 2009 is a Second Generation Prius. Is it possible you meant 2010 and typed 2009? There is a difference since 2009 was the last year of the Second Gen Prius and 2010 began the Third Gen Prius.

 

i think in slovakia, gen III might have begun in '09.

 

In most places in the World they use the year the car was sold and registered as the model year rather than the following year which seems popular in the US. My car was sold and registered in Nov 2009 and is a 2009 gen3 Prius. It is quite often confusing to those who do not reside in the US to have a 2009 registered car refered to as a 2010 and a 2010 as a 2010 unless it was sold later in 2010 at which point it's a 2011.

 

Wow, thanks guys. I stand corrected!

 

Welcome, Miso.

I don't know how flat Austria is--Austrian Alps come to mind.

Instantaneous fuel economy wildly fluctuates. Ignore it. I see single digits just after buying gas pulling out onto the highway.

To paraphrase Obi Wan, your senses deceive you. Don't trust them. I've been on mountains where the GPS shows increasing elevation when I perceive I'm going downhill.

Those short breaks also take a hit. At rest stops I'll turn off the climate control & lights and lock the car preventing start up cycles.

I'd be thrilled to get 54.7mpg (US) on a 700 mile trip.

 

Welcome to PriusChat!

I concur with the GPS suggestion and would add you might want to consider getting a Prius-aware scanner. I'm using a ScanGauge II for normal driving but there are alternatives. They provide engine and temperature metrics and a Prius-aware unit can read out stuff like traction battery voltages and Prius unique metrics.

Are those Imperial gallons? I'm used to seeing folks outside of the USA and UK using liters and was wondering.

Any history on the car?

Bob Wilson

 

Forgive me for being naïve, but I'm new to Prius ownership. Are you saying you leave the car ON, but turn off the A/C, radio and lights, and lock it while use the restroom, etc., at a rest stop? How exactly does that save gas? And what else does it save?

 

At highway speed, the engine is constantly charging the battery. Like many have said, you're probably going up hill when the terrain looked down hill. Also you can tell if you're going up hill or down hill just by the pressure in your ear.
There's no start up cycle once the car is warmed up. If you restart your car at 185f, it'll drive like you never stopped. Also, if you don't shut down, you risk draining the HV battery which will cost you MPG for several miles to try to charge it back up when you drive.

 

That was my thinking, but being new to Prius technology, I'm never sure. I see so many opinions on how to operate a Prius and much of it defies traditional practices, and sometimes logic.

 

You might want to consider getting a Prius aware, OBD scanner. Then you can easily test some of these claims which some in three flavors:

1. Consensus it works
2. Difference of opinion but either way works
3. Uh Oh, someone without a clue

Bob Wilson

 

I have very limited experience driving the 3rd generation Prius, but if the car had just recently been draining the battery when driving uphill or accelerating then it may have been generating electricity to refill the battery even though you were going downhill. It's also possible that there are some driving conditions where the hybrid computer knows it is more efficient to run the engine at a certain RPM or torque load and generate excess power into the battery rather than having the engine match the present road conditions and run less efficiently overall.

My Chevy Volt does this routinely at speeds under 63 mph on flat roads. I believe the Prius does not do that routinely but it might still do it under some less common conditions.

 

Yes, if the CC is left on the battery most likely will be discharged. Outside temp, state of charge, coolant temp, and length of stop all have an effect.

My threshold for the stop is 5 minutes. I'll have some opportunities this week to see how long it takes for the coolant to drop below 185F.

 

Thanks. I do have an ODB scanner and used it recently to alter the backup beep. I once had to pay to have a false code reset and bought a scanner right afterward. Granted, the payment was for the diagnostic, but it's come in handy to verify other codes were not false and to let me continue on my route knowing the code was for something that could wait until I got home to get fixed. They are inexpensive and easy enough to use. The internet provides most of the information to know what's really going on and then get it fixed without getting taken by a repair shop. Still learning what I need to monitor regularly on the Prius.

 

Excellent!

Do you have a way to use the OBD to monitor while driving:

• engine rpm
• EGR %

My testing indicates the 1.8L engine is most efficient up to ~3,200 rpm. Higher rpm is not bad but 3,200 rpm works best as an upper target. That is when I see the EGR % hit a maximum.

Does your OBD have the ability to record data? Can to replicate the problem and record some data?

One of our members, "Frank"(?) from Spain has done some excellent studies using a recording OBD. Sorry, I don't have a handy link but perhaps someone else might have a link to share to Frank's methodology.

Bob Wilson