Why do Hybrid cars get worse gas mileage on the Highway vs City?

Question

I went car shopping this weekend. On the Hybrid cars the mpg rating for the highway driving is worse than city. This is complete opposite from gasoline cars that get better on the highway. I don't get it?

Answer 1

Hi,

this is a bit of a complex question to answer properly, get comfy...

For any vehicle, the most energy is used to get it moving from a stop or a slow speed. Once the vehicle is moving, it takes less energy to keep it moving, up to a certain point (remember, and object in motion tends to stay in motion; an object at rest tends to stay at rest). So a standard vehicle will use slightly less energy to keep itself moving continously on the expressway than to stop and go on city streets.

However...

Full hybrids, like the Prius, use a regenerative braking system to capture up to 26% of the heat energy lost to brake friction and use that recaptured energy to recharge the nickel metal hydride (NiMH) battery bank in the trunk area.

Braking with a hybrid, at it's most basic level, is done by doubling the distance you normally stop at. At that double distance, take your foot off the accelerator and either coast, or even better, barely press the brake pedal to engage the regenerative braking system. This will shut off the gas internal combustion engine (ICE) much sooner and create as much electricity as possible.

When you press on the accelerator gently (imagine there is an egg under the accelerator pedal and you want to roll the egg out, not crush it), you will move under electric power only. The ICE should not fire up.

However, the ICE will fire up pretty much continously on the expressway because you will be above the momentum threshold the electric drive can move the vehicle at. Electric motors are great for getting things moving, but not so great for keeping a large, heavy vehicle moving through the air at 70 mph.

So, driven properly, you should use the electric drive more and the ICE less around town than you would on the expressway. Less ICE use = less gas.

Answer 2

Hybrids are designed to eliminate the poor gas mileage that you get in the city. The city-hwy. mileage ratio is reversed for this reason:

When travelling slowly or not moving at all, the gasoline engine shuts off and the electric motor takes over the propulsion system while the power demand is low (maximum 15-20 mph), which solves the city mpg dilemma. However, more power is required when travelling on the highway in which case the gas engine works and the electric motor recharges. When even more power is needed, both gas and electric engines work simultaneously.

In a nutshell, hwy is worse than city because the gas engine is on all the time on the hwy and on half the time in the city.

For more information type, "How do hybrids work?" in the Ask.com search engine.

Answer 3

The truth is a high fuel mileage vehicle, such as a VW diesel, gets almost the same fuel mileage as a Hybrid does. The 'conventional' vehicle costs much less, will run much longer with routine maintence than hybrids, has no ultra expensive batteries or fuel cells to replace and can be repaired at almost any mechanical/collision shop. The hybrids have to be transported to a dealer just to power-down the batteries before removal or they will be permanently damaged. Hybrids may be a step in the right direction but only time will tell if the buying public will vote for or against. Just check the dealer lots -- since the last fuel scare hybrids are now gathering dust and the dealers can't even fire-sale them.

Answer 4

I think it's because they use the electric motor to get the car moving because electric motors make an enormous amount of torque with very little RPM's and GETTING the car moving takes more energy than keeping it going so with the assistance of the electric motor you save gas in the city (stop and go traffic). On the highway you'll be using the tiny little gas engine that will need to be at nearly 3000 RPMs to keep the car going 60 mph. So it's working it's *** off to keep the thing going.

Basically the hybrid-ness of the car saves you gas in the city or stop-and-go traffic...but a plain ol' Civic will get close to the same mileage on the highway without the high buy-in of the hybrid model.

Answer 5

Hybrids get worse fuel mileage on the highway than in the city because of their engine/generator configuration.

In order for the batteries to get charged in the Hybrid system, it is dependent on chronic stop and go traffic. There is a fly wheel that moves with the axle, as soon as you slow down, or hit the brakes, the energy that the flywheel has runs a generator that charges the batteries. And as the stop and go traffic goes, since you're not getting near the speeds you go on the highway, the car will run the electric motor more, especially when you're sitting at a stoplight.
Now, when you're on the highway, you're not stopping or slowing down significantly to run the generator enough to create enough energy to power everything in the vehicle, so the internal combustion engine has to run.
I hope that helps.

Answer 6

Theoretically, when driving in TRUE city situations (as opposed to around town) the car will work on battery power only between lights or when creeping along in traffic.

This only applies to true hybrid cars though. There are several hybrids that are hybrids, but aren't capable of running on electric only, like a true hybrid.

I drive an '03 Prius and I track every drop of gas it uses. It actually gets better highway milage than around town. The car is rated at 48MPG, but I average 41 throughout the year. In winter, the MPG drops drastically, due to longer warmup times and lower tire pressures and snow.

I spent 3 days driving throughout New Hampshire and actually got better milage than the EPA estimates... 51.2MPG. On slight downhill slopes, the car switched to all electric even at 65 MPH.

Answer 7

I think because it uses electricity in the city and gas on the highway. Yeah hybrids don't gsave you on gas as i thought.
Why dont u take the streets home instead of highways??