ColinBarber

Welcome Jes

These are the official figures for the facelift models - S has 15" wheels, the others have 17" wheels. 16" would be somewhere in-between. You should be able to achieve an average above 50 mpg in a CT.

These are suitable for your vehicle and are quite cheap (under £5 each in the US). They aren't as high performance as the OEM plugs but not sure you would notice any real difference.

Definitely unrelated. The Nav firmware doesn't touch the body ECU and other components to cause a change in behaviour. Lexus washers only work when the lights are on.

Big Rat posted a pic in this thread:

yeah my 13 plate also did it. Not sure if it is the inverter or electric motor but it is a bit like a low pressure turbo noise.

Given the plugs and coil pack has been replaced then I would assume it is a fuel injector not working correctly as it gets hot. Injector three would make most sense to investigate - either move to another cylinder or test/replace. The P0300 random misfire is common for a fuel injector problem as the ECU doesn't always detect the correct cylinder. P0171, too lean, also makes sense if the injector isn't firing correctly. If you move the injectors you will need new o-rings to seal them. At that age the old ones will definitely leak if you try and reuse them.

Tyres are the correct size and pressure so no problem there. If these are the small mound speed bumps, that you can put your wheels either side of, then you may have change how you drive over them as the IS is definitely lower than a Prius but worth checking no covers are hanging down or not installed correctly underneath the vehicle. If you were getting 54 to 58 mpg in a Prius then it isn't unreasonable to see 45 mpg in an IS given that it has a much larger engine, is heavier and less aerodynamic. Low to mid 50s is certainly possible but that would tend to be with longer non-motorway runs.

Welcome John. Moved into the IS forum so it gets better visibility.

https://www.lexus-tech.eu subscribe to the repair manual.

Put some non-conductive grease on the rear of the wheel to stop it corroding to the hub. https://textar-professional.com/textar-training-center/the-use-of-copper-grease-on-modern-brakes/

Welcome 🙂 What tyre size do you have fitted and what pressure are they inflated to? What mpg did you get from your Prius for similar journeys?

I'm confused.

Every 60k miles or every 6 years, whichever is sooner, I believe is the official line. There is probably no reason to replace them due to age, as it is the mileage that causes the wear however I would remove them every 6 years, or at least loosen and retighten them, to avoid them seizing. Don't run them past the recommended mileage, they can wear and part of the electrode can come away and damage the cylinder wall. Not much between Denso and NGK. I alway use Denso, keeps it in the family as Toyota own part of Denso. Don't know how many covers need to be removed to get to the plugs on your age of LS, I'd guess 1 to 1.5 hours in total - hopefully others can give a more accurate time.

All series III RX 450h have HID or LED lights with flat beams. It would probably make sense to disable AFS as that tends to steer more to near-side than it does off-side.

Unfortunately not.

Specs are different in the US. There was an option for massager rear seats, they may have been cooled too?

You don't need to do anything. The HID lights have a flat beam so no adjustment or stickers are required.

Boxing gloves maybe 🥊

Typically performance and stability improvements. Lexus don't provide release notes so we don't know specifically what has changed.

I don't find the cancellation requires any more steering lock on the GS series IV compared to other vehicles.

I guess it depends what you are looking for. Use the search facility, both have been people on these forums - Japspeed seems to get good comments. HKS would be the best option but their exhausts are expensive.

No, flywheel is different. I think they have different bolt patterns (6 on IG-FE and 8 on 3S-GE).

I've not heard of anyone mention this for a series III. Series II, including the IS F, uses the same part - there have been mention for those but are much older and covered more miles. Rockauto do a third party product for £27 + tax and shipping. No idea of the quality. https://www.rockauto.com/en/moreinfo.php?pk=7311212&cc=3353790&jsn=355