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Fuel economy/tank size/things not making sense

17312 Views 11 Replies 8 Participants Last post by  IN VTEC
We bought a new 2016 CT 200h at the end of July. We now have about 3400 miles on it and a number of tanks of gas behind us, and I'm not sure if my observations are normal or indicate something that needs correction.

Driving conditions: most of our trips are under five miles, a handful in the 30-50 mile range, and there's been one 2400 mile round trip from Maryland to Kansas and back. I'd describe my driving style as "normal" -- not aggressive, driving gently but not making special efforts for fuel efficiency* such as pulse-and-glide. Tires are at 35 psi. Fuel has been mostly 87 octane. Many of these miles have been in hot weather with the AC on. We've played around with the different modes, but do most of our driving in ECO.

1) there's a huge discrepancy between the efficiency displayed on the dash and the real efficiency based on the gas pump and odometer. While the computer gives fuel efficiency around 38-40 mpg (currently says 39.4), actual has been in the range 34-38 (36.7 averaged over the last 3000 miles).

2) both numbers are *way* below the EPA estimate (43 city/40 hwy/42 combined).

3) range display on the dash consistently drops faster than actual miles traveled: on a full tank, it's in the 420s... but after 250 miles it's showing 100.

4) user manual says 11.9 gal tank, and that the fuel warning light indicates 1.8 gal remain. My fuel warning light came on when indicated range was about 20 miles. When it said 10 miles, I stopped for gas, and it took 8.6 gallons. None of these numbers work together! It seems like the light comes on when there are around 3.75 gal left, and the range hits 0 when there are 3.2 gallons left? Or is the manual incorrect about the tank size?

Is this cause for concern, or is it just that my expectations are off?

[*]When we first got the car, we tried driving extra gently and specifically attempted to conserve fuel -- but according to the dash display, we found we got better economy by just driving normally.
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There are tricks that most people feel would benefit fuel economy, but in a modern hybrid, the car is designed to adapt to normal driving styles and be at its most efficient without the driver purposefully doing something to aid it. I also noticed that just driving normally tends to work best, unless you understand the inner workings of the way the hybrid system works.

I'll give you my experience on each of your points as someone with a 2014 CT and almost 250k miles on it from daily driving:

1. Most cars seem to greatly overestimate their MPG calculations. The CT is no different. If you look at my log (by clicking my signature), you'll see that I post the car's calculated MPG readout in the note on each fill up, and can compare it to the real MPG Fuelly calculated. While I posted the difference myself for the first few hundred fill ups, I stopped doing it, and figured I or anyone else can do it manually for any specific log they happened to look at.

Suffice it to say that I normally observed a difference of 2 to 4 MPG between the readout and reality. I also noticed that after 200k miles or so, the readout is usually within 1 MPG of reality unless I am near 50 MPG, then the estimate starts going towards the 2-3 MPG difference point.

2. Your MPG will vary on a lot of variables, but the biggest factor is your speed and how hard you accelerate. If I drive 60 or 65 MPH on the highway (that is, with much more highway than city), and stick to gentle acceleration and speed on city streets, I will get 45 to 50 MPG. I don't think the EPA test cycle factors in driving above the speed limit, which is what 90% of us do. Going 70 or above will net you much worse MPG.

It's also hard to get good MPG if all you do is city driving, especially short trips. You will be spending a lot of time accelerating, and may not be able to use the regen brakes as much as you'd like. Also the engine will spend some time running harder to warm up initially, and maybe even charge your battery once in a while if you don't get enough regen braking in. All of this will contribute to worse MPG

3. The range estimate is also quite poor, and rarely have I seen a car that gets it right. Some people have suggested that if you drive the same way with the same MPG all the time, the range estimate will eventually adjust. This is not true based on my experience. Due to how I drive, I can usually hit a maximum range of about 570~ miles. I always hit 0 range when I have around 150 miles left to go.

4. The fuel gauge, just like the range estimate, is very conservative. Most manufacturers try to give you a little warning by showing you nearly out of gas early so you can still drive as you look for a gas station. Toyota/Lexus seems to go really far with this and give you a very early warning. My mechanic once told me American cars tend to tell you you're out of gas nearly right on the mark, while Japanese cars will do it much earlier, because Japanese manufacturers noticed American drivers push their gas tanks to the limit before refuelling. And so in an effort not to overload the fuel pump (which in many cars, gasoline is used as a cooling factor for the pump), the low fuel light comes on early so that the fuel pump will last. He told me that he almost never sees replacement fuel pumps for Toyotas/Lexus models. One of the many tricks that help maintain the Japanese car's reputation for reliability.

I can tell you that I have run out of gas once in my CT, and managed to limp to a gas station on battery power alone in EV mode. When I filled up, I got 11.6 gallons in the tank, I believe. In another fill up, I ran the car very close to empty, and was able to fill up 11.8 gallons. Very inconsistent and odd.

All of this seems to be pretty normal for most of us, so you have nothing to worry about. Once you find the difference in MPG in your car from reality, you can reset your Trip meter after a fill up, and use that, plus the MPG estimate, to figure out a much more accurate range estimate.
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Thank you! And thanks for mentioning Fuelly. I was basically tracking the same info (except prices) on a spreadsheet, but it seems it will be easier to analyze the data with Fuelly. So I've signed up and input my data so far.
Lexus CT 200h (Lexus CT200h) | Fuelly
No problem! Glad to help.

Ya, fuelly helps in not only logging, but you can share the data.
Hello everyone,

Think I'll just add my questions and two cents on this thread instead of starting a similar one. I just recently purchased a used 2013 ct with 58k miles on it. I've been doing my hardest to get to the advertised fuel economy and it's just not happening. In my last tank, I managed to get 37.5 mpg and I had to drive the car mostly on eco to get that.

My commute to work is 5 miles each way and I'm aware the engine has to run more to warm up the system, but it seems like I have to at least drive a good 3 miles before it starts being efficient. Is that normal?

I used to sell Toyotas and I remember when the second gen prius came out, I could take one that's been on the lot for a few days for a client to test drive. I recall the car would accelerate faster on the electric motor to reach 25 mph, then the combustion engine would engage. In the ct however, I have to go slowwwly on the gas pedal to get the car to accelerate on electric alone. In a parking lot, that's perfectly fine. On the road however, the drivers behind me don't have that kind of patience which I totally understand. The ct from a full stop, just accelerates much slower than what I remember a prius used to on electric alone, and that is the part which is most crucial to better fuel economy.

Also, I'm not sure how some claims to get similar mpg on sports mode as they get on normal or eco, because that mode revs the ice so much that my mpg tanks a lot. Even lite pressure on the gas pedal rockets the ct forward. So to those of you who gets anything over 35mpg on sports, how?

Lastly, I tend to get better mpg on the highway. Perhaps it's because the car has had enough time to fully warm up the system unlike my work commute that is only local. However, hybrids are advertised to get higher mpg in city driving so I'm quite perplexed and disappointed why it's the opposite for me.

I read somewhere on here when the vehicle is on sports mode, the electric engine runs with more power, what about when on normal? I wish I could have more power from it from a full stop.

Thx for reading.
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Helexus, I'm guessing that both you and I are getting killed on economy because the majority of our trips are too short. Like you, we seem to get better mileage on the highway -- but it's probably because our non-highway trips tend to be so short. The best mileage I ever saw on the dash display was around 44, and that was when I did a longer trip (12 miles each way) without taking the highway.

As for economy in the different modes -- I haven't actually found a great difference. It may just be that the inefficiency of all our short trips swamps any difference between the modes.
Azamiryou, I have been experimenting lately and I think I might have just made a little discovery today. Last night and today, I decided to drive the vehicle only in sport mode. Even though the vehicle is more aggressive in that mode, so is the electric motor. After I started the car, I waited for the ice to fully turn off after it started running. Not only was the car able to start taking off on electric alone but since I was on sport mode, it took off faster, which alleviated my early problem of very slow take off on eco.

Furthermore, at red lights, better use of the electric motor happened like I remembered it on the second gen prius. One last observation I made was that the car managed (or used) the electric motor much more on cruise control. Going at 40mph on cruise on flat surface, the tc would use the electric motor equally as the ice. However, when I tried to maintain that same speed by slightly keeping the throttle down, the system mostly uses the ice with electric pitching in spontaneously.

Needless to say, my mpg went from 35 to 39. So I think if I keep this up for a week, I should (hopefully) reach 40+ city. I hope you and anyone else can use any of my little experiment findings to your benefit.

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Short journeys and air con are a killer on mpg. I don't have this trouble in the UK. This is yesterday's Fuelly result after a fill up.

This was 90% town driving and a little motorway. This is just "Normal " mode and very mixed driving. I never look for EV mode as I drive it like a normal car. I've tried driving using electric only as much as possible but this is when my mpg drops right off. It's starting to get cold here now so no doubt the mpg will be lower next fill up.

Sent from my iPhone using Tapatalk
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1. Yes, my computer MPG is exactly 3 MPG higher than my actual calculated one (from fuelly). The computer is overly optimistic. :)

2. I could never get the local driving MPG higher than Highway. My Highway commute MPG is 45 MPG. If I am off on a long weekend and fuel up right before.. I can see my local driving MPG is about 38'ish MPG.

3/4. Fuel tank is 11.9 Gal. The Range/Gauge is set to use about 8.5 Gallon. That's why you see it empty around 8.5 Gallon used. The rest are reserve fuel. The reserve fuel is also used to cool the fuel pump, so you don't really want to run it to empty all the time. I did try it once to go another 120 miles after Range shows 0 and I didn't run out of fuel but I did have to full up about 11.2 Gal.
I know I’m very late to the party but after being perplexed by my new (to me) used CT and why my MPG seemed to not add up correctly I googled it and ended up here. You all talk about everything I have experienced in the past 3 months with my car! (Which is the best car I’ve ever owned personally). My average highway/city is 37-41 depending entirely on how aggressive or passive I drive.
One thing I will note in my experience I am able to get better city MPG in Sport mode which I found odd but after a while it’s easy to see why.. I accelerate to my cruising speed much zippier and faster and I am then able to almost entirely let off the throttle with a very slight push and maintain the 90+ for a very long stretch.
Not sure if others have had the same experience as me but I tend to get by far my worst MPG in ECO mode and I’m assuming this also has to do with the acceleration. Which is almost non existent in ECO mode. The electric motor as others have pointed out is also much quicker to respond and accelerate in SPORT mode.
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I think you are correct. Getting to speed quicker with greater initial input from electric motor would result in less run time for the ic engine. The eco mode is most useful once you are cruising on the freeway and maintaining speed. I only do short trips and the trips are over just as the engine is fully warm. I only get 36 mpg. I am glad I read your post because I think I would get better mpg in sport mode due to my driving habits.
I have observed a 2 to 4 MPG (~3 MPG avg) disparity between indicated and calculated over the last 7-8 years.

The major factors that affect fuel economy achieved:
Wheels speed, instantaneous and average (sweet spot is 40-55 mph then drops quickly after 70 mph, or if too slow or stop/go)
Winter vs summer blend fuel (10%)
Grade (duh)
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