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Prius and mileage

I have an '05 Prius. For the past couple of years I have only been able to achieve 34 or maybe 35 mph. I have read the various tips for good prius driving and attempt to do them all. I brought it to my dealer for various regular service appt and I mentioned it everytime. He has no answers. I suspect he thinks “it must be my driving”. I don’t think so and in fact my husband used it for a week or so and could not do better even though he was driving on a high way whereas i am mainly with a town.

Actually driving a Prius on the highway doesn’t get you better mpg that urban city driving.

If you are in a cold area of the country your mpg in winter is going to be worse than you mpg in the warm summer months.

Your gas mileage is actually very good since you travel the highway with the Prius. The best gas mileage is obtained in the city. Your driving style has everything to do with fuel economy in ANY vehicle…car, truck, RV or boat.

Ah, another Prius low mileage thread…Things must be getting back to normal in Toyota Land…

Even on the highway, you should be gettig well over 40. I did, on my '07. Are your tires underinflated? Many Prius drivers use 42/40.

Do you have the OEM tire or a different tire on the car?

The dealer - where we service the prius (Toyota Dealer) just put new tires on the car. They had been the original tires. The mileage has increased slightly since the new tires, but it is now 34 -35. I appreciate any ideas.

The best gas mileage is obtained in the city.

Actually it is the most mileage improvement, attributable to the hybrid effect, is obtained in city driving. For the most part highway driving will not be improved by the hybrid technology and may even be reduced since it is carrying that additional weight.

The current advertised mileage for Prius is 51 city and 48 Highway. If the car actually does better in city driving I believe it must be due to lower average speed where wind resistance is negligible… Keep in mind that ALL forward motion of the car ultimately derives from the fuel consumed. The battery is only a sponge… that can store energy directly from the engine or indirectly from the kinetic motion of the car as when braking…but which of course came from the engine to begin with.
There is a case of beer on this :wink:
Comments welcome.

“If the car actually does better in city driving I believe it must be due to lower average speed where wind resistance is negligible…”

No it has to do with regenerative breaking. When you break…the breaking recharges the hybrid battery.

I’d post this on priuschat or another Prius forum, you’ll probably find some Prius owners with some possible solutions. Me, I’d find another Toyota dealer, see if they have someone that can help.

Mike, lower average speed yields higher gas mileage, regenerative braking is how that is accomplished in a Prius. Maybe its just semantics here.

I know lower speeds yield better gas mileage…I was responding HOW the Prius gets better gas mileage when driving in the city as opposed to highway. Non-hybrid cars…it’s the other way around.

I will take issue with Mike and perhaps you, Keith. First to Mike: Yes, regenerative braking will put energy into the battery. But where did the energy come from in the first place? It had to be the moving car… which one way or another was powered by gas. The regenerative system helps recycle the energy normally lost to braking, but it’s not “free” energy. The regenerative system is nowhere near 100% efficient. On the highway you seldom need to brake, but do you think you would get better mileage if you accelerated to 60 then regeneratively braked to say 20 and then accelerated again…etc?

And Keith: The beauty of the hybrid is a low power engine that is optimized for a single speed (I believe) which is why it can be small and efficient. It keeps the battery charged which can then dump extra energy to cover accelerations and maybe help with short hills; inevitably the battery will be recharged via the engine. Most cars have an over-sized engine which works less efficiently but over a wide speed range, and has the extra power to cover acceleration requirements. Agree?

Regenerative braking doesn’t just happen when the driver presses the brake pedal. It happens while coasting on level ground or downhill as well.

“The regenerative system is nowhere near 100% efficient.”

Never said it was…Just that it IS generating SOME energy while driving in traffic…

When on the highway you’re NOT generating ANY energy…So the difference.

"On the highway you seldom need to brake, but do you think you would get better mileage if you accelerated to 60 then regeneratively braked to say 20 and then accelerated again…etc? "

NO…Remember that driving in city traffic…you’re driving much slower…and using the brakes more…Baking on the highway kinda defeats the purpose doesn’t it.

…but if you were driving on the highway in hill country or mountains, regenerative brakes would be in use when you coast downhill.

Chriscartalk2 I agree with you, if todays hybrids worked the way you think they do. Most, if not all Hybrids today are a hybrid of the original hybrid concept.

The original hybrids, which were homemade cars, did not have a transmission or driveshaft. They used a generator in place of the transmission and an old 28 VDC jet start motor hooked to the rear end. Now for driving across town, the engine would run at a constant speed simulating something like say 20 mph and only charge the battery. The battery would power the electric motor driving the car in its constant cycling between 0-45 mph. Regenerative braking was a luxury that was not available to the builders of these homemade vehicles. The Honda Insight is a true hybrid in the original sense and it has regenerative breaking.

Todays hybrids have a transmissions and driveshafts. The electric motors give a boost during acceleration and act as generators to recharge the battery during braking. The regenerative braking is much more crucial in this scheme because most of the driving is done by the engine.

Now for the reason I came back to this post today. I was driving and I noticed that another vehicle ahead of me had something flapping under the vehicle. I see this every once in awhile but don’t give it much thought, but today it made me think of this post, and many others who have posted here wondering why their gas mileage has suddenly dropped. This covers all types of vehicles, not just the Prius.

If something is flapping under the vehicle, like the plastic “skid plate”, it is going to increase the drag on the vehicle. This is something that I don’t think any of us would notice. After all, we can’t see under our own vehicles while driving down the road and I’m not sure it would be heard either.

I have on occasion seen where the side of the rear bumper comes loose and sticks out like an air brake on a jet.

Anyway, it may not be the reason, but it might be worth looking into.

I’m a member of several gas saving forums with some Prius owners on them maybe someone on one of these forums can help you out.