RX 450h - what is a 'normal' mpg return?

[StretchedLexuses]

Hi all,

Apologies that there are existing threads linked to this topic but I wanted to probe what a normal mpg return looks like on UK roads for a gen 3 RX 450h? I got a 2010 with 150k last week and whilst the car is generally very good, I have been a tad disappointed with the mpg. I've not done a long motorway run yet but on some mixed, very careful driving, I'm just about managing 30mpg. With such pronounced effort to be economical, I was hoping for 33mpg. What generally hits mpg hardest in these cars? Can a higher tyre inflation help, e.g. 40 psi? It's got 13 Lexus main dealer service stamps so surely it's well oiled and spark plugs have been changed (i know at least some have from the myLexus app). Ride is a bit choppy and suspect rear bushes have some play but keen to hear people's thoughts. Is 35mpg possible on a long motorway run with controlled speed?

Thanks all...

[HPS13]

According to the Fuelly website, the average mpg for a 2010 Lexus RX 450h is 30.6 mpg from a sample of 74 vehicles so your 30 mpg may be correct. 

With regards to tyre pressures, I would recommend following what the owner manual states. Naturally on a motorway drive you will expect to see your mpg increase in normal conditions. 

[StretchedLexuses]

Fuelly quotes in American gallons though, which would imply 36mpg in a UK setting given the 20% difference.

[HPS13]

Fuelly has a menu on the home page where you can select 'UK' for the units rather than the US option. 

UK value is 30.6 mog. 

[Stevo11]

I bought mine in Jan, 4800miles since, Avg 31.44mpg ... I found it took about 4 weeks for me to adjust to how to drive these for best mpg, ECO mode on/off doesn't seem to matter.

On the majority of my longer distance journeys I pull either a boat or a tall covered trailer so factor that in.

60mph+ really hits mpg, scooting around town it'll easily go to 34mpg average.

My best over a tank was 35mpg.

[Spottedlaurel]

Unless you're doing 50-55mph on a motorway and can manage doa bit of coasting it's unlikely you'll see an improvement there. At 70 you'll just be running on the petrol engine all the time.

I normally get an indicated 34-35mpg, on a mix of 50mph A-roads and tootling through towns and villages at 20-30mph. That's after 5+ years of getting used to it.

[Cypry 1]

 2010 RX450 Premium 95000mls

My average is about 31mpg on local journeys but on a run I have had as much as 36/37 mpg.

However please be prepared for a drop to 27/28 mpg in winter.

Bear in mind that the size of the vehicle, weight and the V6 engine but this is still better than you would get with other V6 SUVs.

[StretchedLexuses]

Thanks for the intel. I'm getting 29mpg on mixed driving so far but on the more local and extra urban side (few runs above 50mph). Does make me think that maybe some cells are failing as I've been trying to make the most of engine braking and general braking too, and certainly havent been heavy footed. Feel like I should be getting 32mpg. Spark plugs were last replaced by Lexus main dealer just over 3 years ago. Does a failing 12V Battery make any difference? Haven't checked tyre pressures on the 19inch wheels yet but the ride quality is absolutely shocking IMO. Constant vibration and judder with every road contour eliciting a reaction, even on the motorway. I read about the firm ride but this is kind of ridiculous. Rear bushings had an advisory so perhaps that's part of the problem there? Comfortable as the seats are, constant cabin movement grates.

[Stevo11]

I don't think the Battery will make much difference tbh and from what I've read, very unlikely to fail. Finding the sweet spot between accelerating and coasting on the pedal (where it keeps the speed constant) took me a while to find.

Have you air suspension? Which brand shocks are installed?

[MUDGUTS]

I get 40-42 on a run from Chesterfield to Hampshire/Surrey regularly. 95% motorway. Speed between 55 and 75. 2009 RX450h 155k regularly serviced. I think Tesco 99 or Shell V-Power helps. 38.5 would be my worst on this journey. 42.5 best. That’s average of 42.5 on the 400 mile return journey. 
 

You have to totally minimise acceleration and use of brakes. Obviously this is not always possible. If you plan the braking that is required effectively that will help maximise regenerative braking; keeping the needle inside the blue zone but not letting it drop to the bottom or any braking past that will not be regenerative. The more you can coast when meeting slower traffic the better. I don’t use the ‘eco’ setting at all or A/C. I think it’s less generally if wet/dark etc.