100,000 Mile Service and Fuel Economy

[Fraser J44]

Hello everyone,  would really appreciate some advice on an issue I have.   About 3 weeks ago I took my 2006, 400h into my local garage for a full 100,000 mile service including a timing belt replacement.  I've used this garage for a number of years with previous cars and as much as anyone can trust a garage that isn't run by a family member, I trust them and their work ethic.  Since the service I've noticed a drop in my average MPG down from a very nice 29mpg to 26mpg over the last few weeks.   I haven't changed my driving style, which is nice and easy, with the odd squirt on the throttle when I need it.  As far as the fuel.  I normally fill up with the Tesco's premium momentum.  On my last tank I filled up with BP Ultimate.  Coming to the end of that tank and there is no change.  I'm about to go back to the garage and ask some questions and being a complete novice as far as engineering and car mechanics is concerned I wondered if any of you could shed any light/thoughts as to what might have caused the drop.  I should say that the full service plus timing belt change cost £640.  I did pop into my local lexus but they were charging in the region of £900 plus.  I'm wondering if the aftermarket parts my garage would have used might be the problem.  Would appreciate any thoughts you have.  Many thanks in advance.  Fraser

[true blue]

Hi a full service should not reduce your fuel consumption ,most people would expect quite the opposite . How many miles have you covered since the job was carried out ? I would take the car back and get them to check for any fault codes ,which may show if any mistakes were made with the belt timing etc . The only other thing I can think of is they would have disconnected the Battery which would re-set the ECU when reconnected ,This learns your driving style ,so will restart from a default position ,re learning it over time .I do not know how long this takes so if you have not done many miles it may improve  Let us know how you get on 

Dave

[Fraser J44]

Hi Dave, sincere thanks for you thoughts. Since the service I made a return trip to Devon, from London so I'd say I've done a good 700 miles.   I'll ask about the ECU reset.  What I've noticed is that the full tank of Momentum fuel which used to last two weeks is now lasting a week and a half.  A little frustrating after spending £600 plus.  I'll take you points on board and feed back to garage.  Thanks again.

[rayaans]

Using a different type of oil can reduce fuel consumption. I believe the RX400h's use 5w-30.

Might also be worth checking tyre pressures - too low and they'll lead to more drag and less fuel efficiency.

You could also blame the colder weather as it will have an impact (engine needs warming up more)