GRussell

Hi All-

Longtime lurker, but finally registered today. Bought a 450h about 6 months ago, and absolutely love it. Took a little while longer than expected to break in, but after 4k miles, we were finally hitting the target mpg, and we're routinely right around 30 displayed, 29.5 calculated.

Question for all of you. I asked my dealer, and he was unable to answer it. I've also searched quite a bit, and can't seem to find the answer. "What is the most efficient speed to drive my 450h"? My gut feeling would be somewhere around 40mph. But, I'm looking for something a little more concrete/definitive/authoritative than my gut. Is this value specified anywhere?

Thanks in advance,
-Glenn

Cruiter

Glenn, welcome to the board. Just for reference there is a separate section below for the 450h.

Yep, you're getting the good mileage and possibly can improve on that but would depend on your route and driving style of course. RE: your question about the most efficient speed, that's hard to answer. If it 'was' 40mph, I doubt many people would be able to average that kind of speed so it looses it's relevance. I'm thinking you will find the most efficient speed better expressed as driving style and within the speed limit. For instance easy starts, steady speeds, and gradual stops will get the most mileage. This past week I made a trip from my home to Milledgeville using mostly state highways where the speeds vary from 55 to 65 and a 20 mile stretch in interstate where I set the cruise at 70mph. It's a skosh under 150 miles each way and my trip averaged just under 32mpg with temps in the low 90's. But with shorter around town trips I'm closer to 30. I keep my Michelin Latitudes at 32 cold and they climb to between 34-36 psi. If you use your smart phone you can d/load and app called Fuelly. It helps keep exact mileage and it's kinda fun to use.

Good luck, sharp looking car

TexasRxh

Glenn, welcome to CL. I'm sure we'll all look forward to hearing more from you now that you've achieved "break in" on your 450h.

Jim, one would naturally think that easy starts would get you the best mileage, and it may. My experience seems to indicate that I'm better off not lingering in the 10-15 mpg range while I ease it up to speed, but rather accelerating moderately to speed, then backing off. The mpg gauge shows 5-8 mpg that way but for a much shorter duration. I wonder if anyone has done a scientific study on this??

RXSF

I would think from 30-40 is the best speed because that's when you can really just use the electric motors to power the vehicle

Cruiter

That's for a very limited period only. On level ground 4 miles would be close to the limit. Then the ICE cuts on to not only power the car but charge the batteries too.

RXSF

What I usually do if we are on a long stretch of straight road is run on electric at 35mph and then just purposely kick on the ICE for a bit to get some juice. I then let go of the gas pedal to turn off the ICE and repeat this process

VVRX

I believe this is probably a common practice amongst hybrid owners.

TexasRxh

The highest constant speed I can keep the vehicle going is around 35. It will do that until the ICE engages. I can do 40 but can't seem to hold it there long.

I also use EV Mode in the 'hood but you can't go above 25 or it deactivates.

go3Ds

Glenn,

Welcome to Club Lexus, and for the good looking pictures of your new car. Great color choice, same as mine.

Light touch on the gas pedal, while complying with speed limits will give the best mpg. This does not factor in weight, temperature, type of gas, tires, weather, stop and go etc. Anytime your electric motor kicks in, even at 70mph, will improve mpg. You can do better going slower if you don't mind being honked at a few times. I love keeping an eye on the gauges for when the electric motor helps out, either partly or completely.

The optimum speed for me is about 35mph on level roads. I have several opportunities on roads to drive this speed, and love it when I can go a few miles without using gas. One of the many joys of owning a hybrid.

GRussell

Hi All-
Thank you for all the replies.

I agree, though I still think my question is still relevant. For example, sometimes I have a choice between a highway with faster speeds, or some back roads that are shorter. If I knew the car's ideal speed, then this is one factor that could enter the decision making process.

It just seems to me that this should be an easy question for Lexus to answer. I'm sure the engineers and test engineers know this value. Put a car on a track, measure the MPG at a series of speeds, fit a curve through it, and you'll see the most efficient velocity.

Anyone got a test track and some extra gallons of gas?

-Glenn

GRussell

It seems like we're all flirting with the same range of numbers... 30-40 mph, so it's good to know that my gut feeling agrees with most of yours. Now, if we could further refine to a final, concrete number either provided by Lexus, or backed up with test data. Hmmm.....
-Glenn

BertL

I'm perhaps in the minority, but as an owner of an RXh for nearly 9 years, to a large degree, I just drive my truck as I would any other CUV -- as the RXh was probably designed to be. I don't do a lot of intentional "hyper miler" tactics -- knowing my MPG won't be as great as some others, but still better than the non-hybrid rides out there. As I've read this post and thought about it though over the past couple of days, I find in my hybrid (opposed to my non-hybrid toys like my previous 335i and SC430), for some reason, I don't generally take off like a bat out of $&@@, I really do think a lot more about my choices traveling over 65-70 MPH, and I also tend to glide into stops more that I did years ago. All three tactics have just become second nature and while they really help optimize hybrid MPG, are not so bad for "those other vehicles" as well. I guess my RXh have taught me something.

I think it's great some folks use the hybrid and hypermiling tactics as a sort of game to improve their MPG, but for me, I also don't want to be perceived or feel like some old man that has lost his nerve and drives below the minimum speed limit in the slow lane just to get another mile or so per gallon. I'm far from being a maniac or speed demon on the road, but do occassionally use the horses in my AWD and love that look from other drivers when I'm passing, or am up-to-speed at the top of the on-ramp like you should be. My days in the slow lane with others cursing me will come soon enough, and I just don't want to be there before I have to be.

UCSB

Optimal speed has to be somewhere in the 40 to 50 MPH range. I have, on two occasions, taken short 15 mile or so trips in this range and gotten 44 MPG. At slower speeds, like 30 to 40 MPH, the best I have been able to do is a few trips in the 36 MPG range. IMO, it doesn't really matter because under normal operation in traffic you will be back down around the EPA target values.

One thing that I have noticed is that it seems harder to hit the EPA target (30 MPG on my car) values than with other cars I drive. I can hit 30 MPG (or even 31 or 32 in town), it is just more work than in other cars I drive. I can easily exceed the EPA numbers on my Subaru Outback without the crazy hypermiler antics the RX requires. On my daughters Prius, I can easily get over the EPA target of 50 MPG just driving the car normally around town (typically 53 MPG). On the other hand, those cars don't have the power reserve of the RX.

I agree with Bert, trying to squeeze mileage out of the RX gets tedious pretty fast. It is much more fun to just drive it normally.

BertL

...and OP, I agree with you and others. 30-40 MPH seems optimum, but given most us don't live with only flat roads around us, I think coming up with something more specific is unrealistic.

Alpy64

Speed can be much higher when you use a long portion of road descending and as long as the needle stays on the blue zone the 3e3 system is on without consuming batteries untill you go up the separation between blue and green charging zone (before 2013 model).
SO this can be reached at 30, 40 and even above 70MPh