How Do Hybrid Cars Work? - Should I Buy a Hybrid Car?

Real World Hypermiling | Hybrid Autos | Alternative Fuel Cars

How Does a Hybrid Car Work?

The key feature of a hybrid vehicle is its ability to use energy lost in braking and convert much of that energy into generated electricity. In a non-hybrid car, brakes slow the vehicle down by applying friction to the wheels. This friction converts energy of motion into heat energy. In a hybrid vehicle, however, the vehicle is slowed down by engaging the generator. The generator then converts that energy of motion into generated electricity. The generated electricity can then be used to power the electric motor. In slow speed stop and go travel, the electric motor can furnish much of the assistance needed for travel and the repeated braking generates electricity. This is why hybrid vehicles actually get better gas mileage in the city than on the highway!

Advantages of Hybrid Cars

Hybrid cars generate their own electricity and thus do not require use of electric plug-in recharging. This allows them to be used in all areas as opposed to only in areas where electrical recharging is available.
Hybrid vehicles obtain better gas mileage than conventional vehicles, particularly in stop and go city driving. Typically 40+ MPG is common. The Toyota Prius, a fairly roomy mid sized car, gets up to 48 MPG according to this site.
Tax credits up to several thousand dollars are given to purchasers of hybrid electric cars. More info on hybrid tax credits here.
Because the hybrid electric car will utilize the electric motor in slower stop and go city-driving situations, the result will be less pollution in these otherwise pollution-prone urban areas.

Disadvantages of Hybrid Electric Cars

Hybrid electric cars get poorer gas mileage in highway driving situations since they must rely primarily on the gas motor. Thus, a person that does 90% of their driving on the highway with a non-hybrid fuel efficient vehicle like the Toyota Yaris (nearly 40 mpg on highway) may get gas mileage nearly equal to a hybrid. And the cost of the Yaris is a little over half of the hybrid.
Hybrid vehicles, even compacts, typically cost more than a compact conventional vehicle.
Battery life has always been a concern with hybrids and battery replacement can easily cost $3000 to $5000. Here are some folks with some serious and costly battery issues! The good news, however, is that some newer vehicles now come with an 8 yr/100K mile warranty on the battery. Still, are you willing to throw away a 5 or 6-year old car with 100K miles that cost you $25,000 but is in need of a $4000 battery replacement? This gets back to the type of driving you do. For lower mileage city driving, you might be able to stretch those 100,000 miles over the full 8 years. For someone commuting on the highway 30 miles, the warranty will be burned up in as few as 5 years.

UPDATE: According to some posters on this forum, Toyota Prius battery replacement can be done for as little as $1500. I searched around on ebay and found used batteries for a Toyota Prius and Ford Escape Hybrid for under $1000. So it appears that battery replacement costs are coming down fairly quickly.
Repair of hybrid vehicles no longer under warranty might present some issues. But, as more and more hybrids are being purchased, expect auto repair shops to rise up to this challenge quickly.

Should I Buy a Hybrid Car?

If you are driving in low mileage stop and go traffic, then a hybrid will probably be an economically justifiable purchase. Doing the math, if you drive 12,000 miles per year at 26 MPG with a conventional vehicle, you are spending about $1850 per year using a gas price of $4 a gallon. If you can get 55 MPG with a hybrid, you spend about $850 and you save $1000 per year. In 8 years time, that's $8000 saved in fuel costs, thus justifying the extra cost of the hybrid. And, you are doing your part in reducing urban pollution and greenhouse gas emmisions!

If you are driving in nearly all high mileage highway-commuting situations, a hybrid is perhaps not your best option. You will burn up your battery warranty quickly, and your gas savings will not be as high, if much at all, since you will be relying more on the gas engine of your hybrid for this higher speed driving. And even with potentially lower future battery costs, if your gas savings are minimal, the benefits of a hybrid are still minimal compared to initial cost.

For those driving both city and highway, future reduced battery replacement costs may make hybrids an attractive option, with gas savings offsetting initial costs. And a Toyota Prius is a lot nicer vehicle to drive around, with much more room, than a tiny sub-compact non-hybrid.