MPG suddenly gone down

[syd]

Hi All!

 

I got my CT200 in June and since then, I've been averaging about 40 odd mpg on each tank of petrol. I filled up this week, reset my mileage counter, and suddenly my mpg has gone down- dramatically. I'm not only averaging 28mpg. Anyone know why that could be? Seems like a huge drop to me!Insert other media

Cheers

[PaulWhitt20]

Colder weather.

But 28 seems very poor. Have you changed your driving style or the type of driving you do

Best results are on longish journeys on A roads at about 50 mph.

[rhosneigr]

Since having its fist service last July at 5000 miles I have found the mpg has gone worse. I was averaging about 54 mpg per tankful but this has now reduced to 45 mpg per tankful. Driving style is similar, road types the same and the weather has not been to bad since July. I keep meaning to talk to the garage but not done so yet. Must get round to doing so.

[Zotto]

Verify the right tyres pressure, and if the oil is the 0W-20 Toyota. Nonetheless, it is a big difference, even if with worse weather mpg are affected.

[stormchaser]

As stated it's the cold weather coming. 28 is a bit low. These do need the 0/20 oil in them like the Prius and as said tyre pressures too. They seem to be quite sensitive to these if not right. I've got my tyres set to 38psi all round.

This is my latest fuel use using Fuelly.

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[sorcerer]

5 hours ago, stormchaser said:

 I've got my tyres set to 38psi all round.

 

Is that the pressure Lexus states they should be in the handbook/on the car label? If not, I'd be very careful because you may find that in the event of an accident your insurance may be void. A couple of years ago a guy I worked with at the time had been a bit lax about his maintenance routine and was involved in an accident where, on inspection, his tyre pressures were found to be incorrect. His insurance company either refused the claim or reduced the payout, I can't remember which it was now.

[rhosneigr]

My tyre pressures are 32 psi all. The ride is pretty hard at that tyre pressure so without going out to increase the pressure to 38 psi was wondering what the ride and roadhOddington is like at that pressure and surely tyre wear would increase especially on the crown.

[stormchaser]

I believe 32 is what the book says?

I've tried that pressure and found mpg was down. At 38 the ride feels the same and I've got even tyre wear all round across the tyre width. It's certainly made the mpg better. On the Prius forum some are inflating to 50psi and beyond which is damn right dangerous and exceeding the max inflation. So far I've got 6.5mm on all tyres(Goodyear). Since I've just done it's 60K service I've found that mpg is good but the cold is coming and the engine is running a bit longer now on cold start and having the heating on inside after finishing work in the early hours.

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[Wass]

The lexus factory state that in the absence of the correct but expensive 0/20 oil it is permissible to use  cheaper 5/30 oil. This increases fuel consumption dramatically. After my car has been serviced I have started to routinely monitor fuel consumption very closely before and after the service over the same journey. On two occasions , I have changed my own oil and found an immediate improvement of fuel consumption. I have challenged the Lexus garage about this phenomenon however they confirm that the oil used was within Lexus specification...... just as you might expect if they used the 5/30 which is specified by lexus as an alternative. I  routinely buy the right oil and prepare to change it post service. This way I maintain my valuable serviced by main dealer service record and the self funded oil change repays me within 5000 miles. I have now come to regard the service oil fill simply as flushing oil. I have also most recently carried out a routine cold viscosity check of my oil by timing  the flow through a full tundish and have confrimed that the Lexus supplied oil passes through the tundish slower than the 0/20 which I replace it with. I have mentioned it to the dealer once and i now know what to expect. I really dont have the time or the inclination to make any more of an issue of it. This has just confirmed my already low opinion of the motor trade in general. Its nice when I dont get ripped off;nevertheless I do expect to get ripped off all the same.Turning the clock back a couple of decades; In the case of jaguar cars, I would happily buy a car from a jaguar specialist but learnt not to buy one from a jaguar dealer at any cost.