Mk3 Gs300 Low Mpg

1meanmachine · January 24, 2015

Hi guys,

just a quick question for any mk3 gs300 owners out there. My mpg seems a little low. the car is showing between 13 and 14mpg average on the computer. This is all town driving with a light foot. The car has 77k on the clock flsh and has literally just been serviced about 50 miles ago. Is this normal mpg. From what i heard it should be in the high teens.

Thanks in advance Mal.

messi · January 24, 2015

It's probebly due to the cold we are having, the weather can affect the lpg

messi · January 24, 2015

I meant mpg

messi · January 24, 2015

But having said that 13-14 seems abit too low. I get 19-22 mpg

ColinBarber · January 24, 2015

It does sound a little low. After a run it is worth checking to see if any wheels/brakes are excessively hot, you could have a sticking brake calliper.

1meanmachine · January 24, 2015

Thanks for your reply guys. It's just been serviced by Lexus hatfield and they said the brakes were fine. I will check again but there doesn't seem to be any heat being emitted from the wheels. Is there anything else I could look at. Tyres are at 34psi all round.

hunslet · January 24, 2015

yes, 13-14 mpg is a tad low even in the cold and driving around town. I assume your GS is the same as mine was and the mpg resets everytime you fill up. If you fill up when the engine is cold the average starts very low and, in my experience, stays low - very low. I know it sounds like nonsense but if you fill up with a warm engine prior to a decent run then the average starts high and stays high - well highish.

Keeping the car in the garage makes a huge difference this time of the year.

The good thing is that petrol is relatively cheap these days.

ColinBarber · January 24, 2015

I'd try cleaning the MAF sensor. Do you have any documented service information, do you know if the oxygen sensors have ever been replaced?

1meanmachine · January 26, 2015

Thanks again for your replies. It has fLsh and from what I can see the oxygen sensors have never been changed. I'll have a loo in to the maf too.

Thanks.

1meanmachine · February 28, 2015

Hi guys

done a brim test on the car and it has given me 210 miles to full tank. This was pretty much all urban and in power mode. Driving with a light foot. Will do another fill up today and drive it in normal mode and see what happens. Mpg crept up to 16.5.

1meanmachine · February 28, 2015

Forgot to mention. I took it to a specialist yesterday. Japex. Wonderful experience. The man checked my gearbox oil and ran a full diagnostics on the car. Which came back with no faults other than one tpms sensor.

Mal.

messi · February 28, 2015

16 5 is low mpg

1meanmachine · May 7, 2015

Just an update. Car is averaging high teens around town but remarkably I'm starting to get motorway mpg from 30's to mid 40's. Last Saturday I saw 46.9 on a drive up the M1. This way at 55mph. Never thought I'd expect to see that.

Mal.