High fuel consumption (l/100km / EU)

Last summer I bought a 2010 Prius with 130,000 km (80k miles) on the clock. Since then everything has been fine, except the fuel consumption appears to be a lot higher than it should be. Right now here it's winter (3c / 37F), I don't have super efficient tires, I'm not blocking the grill, I have some minor bumper damage and I mostly drive in the city - I don't expect to be hyper-miling (kilometering?), but it seems a lot worse than it should be.

I went to a friendly neighbourhood mechanic (re the bumper issue) the other day, and he said he had a Prius in a few weeks ago that was averaging 4l/100km (58mpg) - mine is between 7 and 9 (33mpg - 26mpg) right now. My measurements are from Sprintmonitor based on actual fuel consumption (the on-board computer records lower consumption), here is the vehicle page if you are interested: Gasoline consumption: Toyota - Prius - Prius MY 2010 - Spritmonitor.de When comparing other models from the same year, mine is 3rd from the bottom

As I said I live in the city, so I do a lot of stop-and-go. This morning I went for a short drive (~20 mins), and the ICE quickly warmed up (< 10 mins) and cut off when stopped at traffic lights. The cabin temperature was set to 16c (60F), the fan on the lowest setting (1 bar) and AC/rear heater off. When driving along the flat I can cruise at around 60km/h (37mph) with the ICE off. When fully charged I can usually drive like this for a few kilometres before the battery gets low - the battery seems to hold charge well, so I don't think there is anything wrong with that.

If there is a small incline I can usually drive up it on electricity alone, but if it's a little bit steeper I start to lose speed so need to accelerate more and the ICE kicks in. When that happens the transition from electricity to ICE is smooth, however the instantaneous consumption gauge jumps to the top, meaning it's consuming >10l/100km. The ICE also doesn't deliver that much more power compared to electricity alone when in the 'ECO' section of the HSI. Often when accelerating, to keep up with other traffic, I have to go high into the 'PWR' section. Usually I run in 'Normal' mode, I've also tried 'ECO' and 'PWR' mode but they don't make any difference to this.

Here is a video of the indicators while driving around the city - not trying to drive good or bad, just keeping up with other traffic. It was mostly on the flat, with a small down hill and up hill section at the end:

If I'm driving along a highway the consumption is lower. At 90km/h+ I can usually cruise with the instantaneous display showing <5l/100km. It's not that much difference, but the best tank I had was 5.2l/100km (45mpg) driving along a highway at ~130km/h (80mph).

So my question is, is this normal? If not, where to start looking into fixing it? Will a Toyota dealership be any help or should I stick with my friendly neighbourhood mechanic (who won't mind investigating things)?

Here are my answers to the fuel economy Q&A:

- Have you read This Thead Yet?

Yes.

- What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations)

7l/100km - 9l/100km (33mpg - 26mpg) this time of year. In the summer it was 5l/100km - 7l/100km (47mpg - 33mpg). Fuel consumption tracked with Sprintmonitor.

- What fuel economy are you expecting and why?

5l/100km (47mpg) - 6l/100km (39mpg) at this time of year.

- What are the approximate outside air temps?

Right now 0c (32F) - 10c (50F). In summer 20c (68F) - 30c (86F).

- How long are your trips?

Usually less than 30 mins, but even after long trips (a few hours) when driving around the city it's the same.

How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night?

Navigation diagnostics section shows it as 11.8V., so I should probably think about replacing it. It was the same when I bought it though, and it survived -25C parked outside over winter If that was the culprit I'd expect to see low EV range too (or is the 12V battery only charged when the ICE is running?).

Have you had your alignment checked? Any pulling or abnormal tire wear?

Nope.

- How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving?

Mainly city driving, stop and go, up to 60km/h.

- What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.)

Flat and gentle hills.

- What are your tire pressures?

2.6bar (37 PSI).

- Is your oil overfilled? (i.e. above the full mark on the dipstick)

No. Had it changed once so far, and it's stayed level the whole time.

- Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.)

First car. I don't have any regular routes as I'm mainly a taxi service for my wife.

- What region/state are you in? (if you haven't set your location)

Lithuania, EU.

- How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking?

Driving normal, keeping up with other cars. Try to predict stops and let it coast before braking.

- What modes are you using, if any? "normal", EV, power, eco?

Normal.

- Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on?

No.

- Are you driving using D or B mode?

D.

- HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to?

16c (60F), the fan on the lowest setting (1 bar), and AC/rear heater off.

- Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15).

Sunny Wintermax NW211 225/40 R18 92H XL.

- If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute?

It's been like this since I bought it.

 

Long story, but yeah they are 18" winters. They survived much better than I expected, and I haven't had any issues with them slipping on ice or snow. The summers are nearly done, and I have the original rims, so I'll try and get some from the low-rolling-resistance thread.

Are there any other checks other than voltage for the 12v? I understand the voltage is a bit low, but it survived two weeks without use while it was between -10c and -25c so it still seems to be in good condition - I haven't seen any weird issues with the dash.

 

Thanks! I want to get it serviced by Toyota soon, as it has only been serviced at third-party mechanics so far, and I'd like to get them to give it the ok in case I have any warranty issues later. Maybe they'll spot some maintenance that should have been done but was missed...

I looked into EGR and throttle-body cleaning - it's not something I can do myself, but I'm not really sure whether that would be an issue here. When I bought the car I got a mongoose cable (to disable the reversing beep and adjust auto-sensing lights) and there had been no DTCs since it was reset 45,000 km before. As I understand these issues can lead to shaking, knocking or misfiring which will log errors but I haven't seen any of those issues.

Next month we usually change to summer tires, so I'll get some 15" from the LRR thread. If none of this helps I'll look into replacing the 12v. I'll post an update with the results!

 

Right, back from the Toyota dealership after having the 'enhanced' 150,000km service. They didn't really say much, and for what they did I'm not sure the €265 was really worth it, but here goes:

- I told them about it consuming 7l - 9l/100km when I took it in, and they said that sounds about normal (I guess they've never heard of this forum, or even read their brouchures then?). However, during the 20km drive on the way back (through the city) it averaged 4.2 (by the computer - so maybe 5l/100km actual) which is better than I've seen, however that trip was mostly flat or down hill and the engine was warm from them working on it, so ¯\_(ツ)_/¯

- I noticed on the receipt the oil was cheaper than what I paid to have it changed before (at a random garage, not a dealership). I checked the receipt from the last place and now see they put 5W-30.... doh.... Toyota put 0W-20 (Eneos Premium), so that should make a difference. That oil from local shops is usually €40, and their price is €60 including filter, gasket and work, so I'll be going back in 15,000km.

- They said the front-right wheel bearing needs to be replaced - this place is full of potholes so if this is the first time they've been replaced it's not too bad. They want €291 for the part, and €86 for the work. Timken seems to be recommended on this site as better quality than Toyota for bearings, but getting one shipped from the US (+ import fees + taxes) would probably be even more expensive.

- When we bought the car we had it inspected at this place and they said there was a panel missing under the engine (plastic bit under the oil pan) and there was some sort of minor issue with the steering. They didn't say anything about those this time though, so I'm not convinced their inspection was very thorough

- They said there were recalls on air bags and brake pump that haven't been done, they need to order the parts though which may take up to a month.

I'll see how it goes for a week or so on the new oil... fingers crossed!

 

Replaced the wheel hub at the neighbourhood mechanic last night. We got a Koyo REPT283716 from a Japanese parts store, which I believe is what Toyota uses as the OEM hub.

At first he said there didn't seem anything wrong, but once we took the wheel off we saw there was some vertical movement. We managed to get the old hub off without removing the axle assembly from the suspension - we put some old bolts in the hole and hammered them, then got an air hammer between the main part and the hub which eventually freed it (watch the speed sensor if you decide to go the brute-force route).

We also just zip-tied the brakes to the spring so didn't need to disconnect the tube - not sure if we even needed to do the procedure to disable brake control, but we did it anyway. When powering it on and shifting into reverse it started beeping and flashing 'Shift into P' - had a bit of a panic, until I realised the drivers-side door wasn't shut properly Took about 1.5 hours, total price €125 vs €400 at the dealer.

Oh and on the way back home, over 20km I averaged 3.8l/100km (62mpg - by the computer). I'm beginning to think the main reason for my poor economy is just the cold and it burning more fuel to heat up the engine. However, when I bought the car it was summer (25c - 35c) and it still wasn't great then - averaging 5-6l/100km. This weekend I'll be going on a longer trip, so we'll see how it fairs with that - I've setup Torque to log the OBD data, so maybe I can get get some charts to figure out what's going on.

 

Yeah until next week. By law we need to have winter tyres until April 1st, so I'll switch to 15" LRR then (or shortly after as usually the garages are full). Summer is coming, it's up to 12c today

 

Still haven't got summer tires as the ones I ordered and paid for were apparently out of stock. Should be getting another set (Nokian eLine2 - rated A A for fuel efficiency and wet grip) this week. However fuel consumption over the past week seems to have greatly improved...

I've done at least 600km since the last fill up and I've still got two bars. The computer is showing an average of 4.5l/100km. I can't imagine any of this really having an impact on it, but this is what's changed:

• Toyota dealership received recall parts so replaced the curtain airbag inflators and fuel tank charcoal canister, and also updated the HV ECU (for the 2014 IPM recall - I haven't noticed any difference in power as others have stated)
  
• With the last fill up I added a bottle of snakeoil - STP Petrol Engine Cleaner
• I reduced the tire pressure (to 2.3atm/34psi) as I got fed up with all the potholes here

The weather has been a bit warmer this week, but as I said in an earlier post, even during summer last year I was averaging 6l/100km. So who knows....

 

FinToy: Yeah your mileage is kind of what I'm expecting, but even during summer I was getting much higher than that. I had the wheels and tyres swapped this morning - already it's so much smoother to drive The previous ones (in my profile pic) were 225/40 R18 - so it's not just that the rims are bigger, they are a lot wider too. I'm now running the stock wheels with Nokian eLine 2 - rated A A for fuel and wet grip so we'll see what that does. I park outside and there is no access to electric, so a heater isn't an option unfortunately.

interesting: Feel free to come and teach me. I can give you a tour of Lithuania I tried one week of driving like a grandpa before posting - sticking in the eco zone when accelerating (one time even a bus tried to overtake me...), and braking softly and very early before stopping to get full regen, but even driving like that the fuel consumption was the same.