SeventyGTX

We are most likely going to be purchasing a loaded Starfire Pearl/Parchment 450h within the next couple of weeks. Since we have never owned a hybrid, I am curious what makes the advertised city mileage greater than the highway mpg, 32/28. We live in a small town in the high Nevada desert, so most of the miles put on it will be on long open stretches. Will we most likely see the bottom end of the mileage spectrum? It's not a big deal as we won't be putting a lot of miles on the car since we are retired, but I'm old school and curiosity is getting the best of me.

Droid13

Conventional cars naturally get better numbers at highway speed because they spend a lot more time at steady speeds, much less stopping and accelerating. Obviously a very efficient way to drive. Any acceleration, especially briskly, is the real killer of good mileage numbers. In most cases, a hybrid is not too much better at mileage at "rated" highway speed because there isn't that much use of the hybrid in this case (braking energy recovery, electrically assisted acceleration), and probably not any better at "real" highway speeds in the left passing lane.

In the city, stopping and accelerating is where the benefits of a hybrid are most noticeable. Aggressive stopping and accelerating in a hybrid will still yield disappointing results, but if driving casually the benefits can really come through.

But even then, specifically to your question, can the efficiencies in city driving be that good to make the mileage as good or better than highway? After all, accelerating still requires a good gulp of fuel, hybrid or not! Yes, in fact. But not from the stop and go mainly, but again from steady cruising, but at city speeds. At up to 40mph cruising speeds Toyota hybrids are hyper efficient. Frequently at these speeds electric only drive can be achieved, or electric/engine combined driving which can yield extremely, sometimes stunningly good mileage numbers. At these speeds in steady cruise, the power requirements are so low that it's simply not practical for a regular car engine to be efficient at delivering such low power output. It's almost like wondering why an idling car isn't getting good mileage, because it's burning extra fuel to do not much of anything. Your ability to achieve rated mileage numbers will depend a lot on how often you can cruise steady at these speeds. This is what brings up the advertised mileage ratings to match or even exceed highway numbers.

While achieving rated numbers can be difficult depending on your own circumstance, actually getting better mileage in the city is not smoke and mirrors, I do find in practice my city numbers routinely are slightly better than my highway numbers.

rsutoratos

my highway is 33 and city is like 20.. my city is nyc. lots of lights and excess idling. Hills do not help as well.

SeventyGTX

That's great highway mileage!

oohpapi44

iTrader: (1)

My numbers are similar for nyc. 28/24 (lead foot on highway). The number of lights will not lets us get better highway numbers as the electric battery is dead within a 1/4 mile with barely any time to recharge.

GSteg

iTrader: (15)

The electric motors help acceleration in the city so you're not spending as much fuel. When I use to drive a Prius around, I find the bulk of the city driving was either electric-only, or electric-gas. On the highway, it's pretty much the gas engine that does all the work.

For the EPA's city test, they try to simulate city driving (duh) with stop and go. There will be times where the engine will go through a series of 20-30 secondsidling to mimic traffic light stops. While your hybrid's engine is off, a conventional car next to you is sipping fuel to keep the engine running at idle. It's only further into the test where the hybrid's engine may actually turn on to charge the battery.

SeventyGTX

That will be tough to get used to..............sitting at a stop with no engine running, hoping it will move when the light turns green.

kitlz

Not exactly. I've seen my best mileage (33.9 MPG) on a highway with a speed limit of 50 MPG and occasional stoplights. The big difference, the road was flat compared to my normal hilly commute. The cruise control wasn't on either. I also had the experience of watching the mileage climb while crawling in traffic on a hot summer day, the gas engine kicking in every few minutes. Instead of being annoyed I was smiling. People around me were probably watching their gas gauge edge closer to E between idling and having their AC cranked up high. BTW, AC on the RXh is electric. The gas engine will kick in when the battery gets low, same with driving around for a long time under electric power (aka 'stealth mode'). It's pretty neat.

Check out 450h mileage thread for other members' mileage experiences.

You'll get used to it after a while. The transition from electric to gas is super smooth and quick. Just an ever so slight delay compared to the 350. I like when the RXh 'stalls" while driving and listening to the brakes when slowing down. Never gets old.

SeventyGTX

Well, I just talked to the dealer and will be test driving one tomorrow morning 70 miles away in Reno, the closest dealer to us. They don't have one with the color and options we want, but said they can get it. I was super impressed with the 350, hopefully this knocks my socks off even more.

Cruiter

Don, while everyone is a little bit right, everyone also is a 'little' bit wrong. It's in the variables and same for myself. Now you live in a desert town, probably flat. If you drive 7-10 miles around town when you crank it and feather your stops and starts you'll probably get as good as or better than hwy mileage. However if you drive short spurts on a cold engine and use more power than needed to achieve the speed you're looking for (easy to do cause it has nearly 300hp) then you'll certainly get better on the highway. And if winter comes, your car is kept outside (cold engine block) your city mileage will decline more due to the cold temps of the hybrid power outside.

User 41924

The easy answer to your question about what makes the advertised city mileage greater than the highway mpg, is that in city driving you will use the electric motors much more frequently. On the highway, you will use the internal combustion engine almost exclusively to overcome the significant resistance of moving a vehicle with less than optimal aerodynamics down the road at highway speeds. In city driving, wind resistance is far less, and your electric motors help offset the disadvantage of accelerating the 2 ton vehicle.

However, mileage is only part of the story, and (in my opinion) it's the less interesting part. If you're as curious as I was about ALL of the differences, I would recommend spending some time learning about how the Atkinson style ICE, the constantly variable transmission, and the environmental systems all work together. Honestly, I gained a lot of respect for my car, knowing all they considered, and the engineering and technology it takes to make a 2 ton SUV a comfortable, functional car that gets great mileage. It may be a hybrid, but you still have to enjoy the car. Lexus shines in that regard.

Cruiter

Best answer yet , thanks Woody.

SeventyGTX

I agree, great answer!