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Best all-time consumption: 64.4 mpg on standard unleaded petrol (95)

The fuel economy in my CT seems to be going down as time goes on. Driving it back from the dealership I saw 65mpg with approx 500mi range on a full tank. Lately I'm lucky if I see 55mpg and more than 320mi range. I'm not driving it noticeably different since picking it up 2 months ago. It's in ECO mode probably 95% of the time. Does the car calibrate itself to different fuel if I fill up with fuel from different manufacturers? I normally keep the tires at 36 psi.

The mpg figures are in UK gallons by the way, so they will sound higher than those achievable in the US.
 

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Fall = colder temps = more gas. Winter will be worse. My best in the summer (no A/C) was 4.3 L/100km (real-world).

Today, I'm at 4.6 L/100km. Temps are about from 6-7C in the morning to 15C in the day. I expect to hit around 5.5L/100km in the coldest winter months (Jan/Feb) - we'll see....
 

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Fuel is formulated differently for cold weather and mileage will suffer as a result. You'll get the best fuel economy in the warmer months. My average since day one is at 53.6 mpg and I have 17k on the odometer. I gave up on eco mode early on. Too sluggish and no noticeable improvement in mpg's. Run in normal mode most of the time. Tire pressure is important. Good job with that but isn't 36 psi a bit high? Should be 33. Keep it in the blue and coast whenever possible.
 

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Doing 45.8 (ImpGal) here after just a quarter of a tank, I'll hope for more on a long run. Need to show off the car to the parents to get the chance for that :) The 45.8 is on a mix of Eco, Normal and Sport, where I've gone for Sport when I'm throwing the car around roundabouts. I go for Eco in nose to tail stop/start traffic where the dulled throttle responses aid Chill Out mode. My driving so far has been 90% urban (max 40mph-ish) with occasional short runs on the motorway.

Tyre pressures - higher isn't great for open road or where you want grip because it makes the tyre surface curve out ... (like what you'd see on a motorbike but less noticable). The curving outwards lowers rolling resistance. I go for recommended psi + 1, with the +1 allowing for what escapes the tyre after you take the pipethingy off.

Cold weather - the engine stays on until it's at the right operating temperature, so it'll stay on longer when it gets cold -> more petrol used.
 

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Covered just shy of 17,000 miles now and average is around 45MPG. mainly motorway driving at 70mph ;) though. On last tank refill managed 38 MPG keeping it in sport mode the whole time - this is lowest I can get it too. Maximum is around 48MPG on a tank in normal mode.
 

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I am noticing a slight drop (from 4.8 to 5.1 l/100). The mornings are cool/cold now but the daily highs are double the normal so I think they have started to bring in the winter gas and that is why I am seeing a change. Wonder what I will get when the temps drop another 35C (85F)!
 

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Since March 2011 until now I have averaged 42.2 mpg with regular gas and a mix of normal/sport mode in mostly stop and go traffic with lights. I have found that sport mode increases my efficiency slightly by a few tenths of a gallon. Have not driven in ECO mode as it is boringly slow and sluggish.
 

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Tyre pressures - higher isn't great for open road or where you want grip because it makes the tyre surface curve out ... (like what you'd see on a motorbike but less noticable).
That would be true if you were exceeding the psi recommended by the tire manufacturer. Unless you set the pressure to 52psi or higher, you aren't doing that with the OEM tires.
 

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Just because they are rated to 51psi doesn't mean they should be run at maximum pressure. Car manufacturers spec tire pressures based on many criteria (performance, handling, braking, traction, etc.) to achieve optimum driving performance. Agreed you can run at higher pressures as long as you don't exceed tire manufacturers maximum.
 

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Just because they are rated to 51psi doesn't mean they should be run at maximum pressure. Car manufacturers spec tire pressures based on many criteria (performance, handling, braking, traction, etc.) to achieve optimum driving performance. Agreed you can run at higher pressures as long as you don't exceed tire manufacturers maximum.
That is correct. Each model car might have different pressure recomendations even though they use the same tire. Use the stated recommeded tire pressure stamped on the car as a guide. Overinflating can cause uneven wear which can negate any savings you might gain from better mpg. Depending on the amount of wear, sudden blow outs can also occur if not properly inflated.
 

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Over inflating is ALWAYS better than under inflating... But running the tires at "Maximum" pressure is stupid, that means thats as high as the tires should ever get, not what they should be at for driving. Anything higher can make them go boom, and just the temperatures outside being warm can increase tire pressure and tire pressure goes up as you drive the car because of heat/friction.

But in general, I recommend running slightly higher than the recommend PSI on the door. For example, running 35 psi in a car that recommends 32psi WILL NOT negatively effect the tires. And tire pressure gradually DECREASES over time, meaning the average joe who never checks there tire pressures will already have below manufacturer recommend pressure within a month after setting the PSI AT the recommended pressure, meaning you will be running low.

If you run your tire pressure low, like say 25psi in a car recommending 32psi, you will cause wear to the outside edges of the tire, which already get worn more than the inside of the tires due to cornering and camber/toe. While running the pressures a little high will just add more wear down the middle which in general is the last part of the tire to wear out. And since you have the pressure slightly higher, your MPG and handing might also improve, and after a month your tire pressures will still be at or slightly above the recommended PSI.

And in case anyone forgot... The entire Firestone/Ford tire fiasco was due to people running their tire pressures BELOW manufacturer recommended PSI.
 

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According to Hankook Tire website, "Generally, the optimum inflation pressure is about 90% of the maximum level."

The OEM tires on the CT are rated at 51psi. At slightly less than 90%, filling the CT tires to 45psi is perfectly safe. Will the ride be as soft as the Lexus recommendation? No. But there's nothing dangerous nor will the OEM tires exhibit uneven wear at 45psi.
 

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45psi is still VERY high (unless its some sort of very heavy vehicle with truck tires). If you filled it up when cold, it could hit 51psi+ when the tires heat up in hot weather.

And at that PSI, the tires probably will show some sort of tire wear change, probably more down the middle of the tire.
 

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My earlier reply I stated 4.6L/100km (increase in about 8% from my best). On the topic of tire pressure, to note that a contributing factor as well as the colder temps is I dropped the tire pressure from 34psi to 30 psi during the last couple of tanks. I prefer the less stiff ride which also means less chances of hearing creaks in the interior.
 

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45psi is still VERY high (unless its some sort of very heavy vehicle with truck tires). If you filled it up when cold, it could hit 51psi+ when the tires heat up in hot weather.
The max recommended is based on them being filled cold. They've accounted for the increased heat that comes with driving the car when they came up with that number.

If you're talking about filling time to 45psi at 32 degree weather and then driving them the next day at 90 degree temperature, then you're correct that they would be overinflated. But where does that type of immediate temperature swing occur?

[/quote]
And at that PSI, the tires probably will show some sort of tire wear change, probably more down the middle of the tire.[/QUOTE]

With regular tires, that's probably true. But we're talking about Low Rolling Resistance tires which are harder than the tires that we've used all of our lives. If you look at the max recommended psi on LRR tires, you will see that it's about 10psi higher than what we've all become accustomed to.

I had a Civic Hybrid for over 8 years. The LRR tires that the Civic used had a max pressure of 44 psi. I ran them at 40psi the entire time with no issues or uneven wear.

One more thing to consider is that Lexus couldn't make a tire pressure recommendation based on the assumption that people would continue to buy LRR tires with a high maximum psi, They have to assume that many people will buy standard tires when the first set wears out. Therefore, they can't recommend a tire pressure that's higher than is safe for standard tires with a low maximum psi.
 

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The max recommended is based on them being filled cold. They've accounted for the increased heat that comes with driving the car when they came up with that number.
Thats not true. Max pressure is the highest point at which the tire should operate, not the max you can fill the tire. Anything after that is beyond what the manufacturer can safely say can be in the tire, meaning you are taking risks.

If you're talking about filling time to 45psi at 32 degree weather and then driving them the next day at 90 degree temperature, then you're correct that they would be overinflated. But where does that type of immediate temperature swing occur?
Tires don't just go up a little when they heat up, they go up 5psi or more in pressure. And that can occur after just a couple of corners. Friction creates heat, and tires are where all the weight of your vehicle come into contact with the ground and all that friction, they get VERY hot.

With regular tires, that's probably true. But we're talking about Low Rolling Resistance tires which are harder than the tires that we've used all of our lives. If you look at the max recommended psi on LRR tires, you will see that it's about 10psi higher than what we've all become accustomed to.
Hard tires have existed forever. Low rolling resistance tires are nothing new, they've just become more important now that MPG has become the important factor in new cars.
I had a Civic Hybrid for over 8 years. The LRR tires that the Civic used had a max pressure of 44 psi. I ran them at 40psi the entire time with no issues or uneven wear.
40psi with a car that doesn't weigh that much won't be an issue. I had a set of tires once that If I ran them below 40psi, they would tramline and drive like crap. They were bad tires though and wore poorly on the sides of the tires due to the rather boxy shape of the tire tread.

The next set of tires I got on the same car with the same wheels I would run at ~35psi and they drove just fine. So ideal tire pressure can and does vary on the specific tire, but usually its between 32-40psi on a car that weighs ~3000lbs.

One more thing to consider is that Lexus couldn't make a tire pressure recommendation based on the assumption that people would continue to buy LRR tires with a high maximum psi, They have to assume that many people will buy standard tires when the first set wears out. Therefore, they can't recommend a tire pressure that's higher than is safe for standard tires with a low maximum psi.
Tire pressure recommendations on your door sill are based specifically on the original manufacturer equipped tires, they don't account for other brands of tires or wheels you might install on the car.
I'm fairly certain this is in all the owners manuals, but I do know when I worked at a dealer and asked that specific question that I was told by the manufacture reps that this was the case.
 
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