For the sake of contrast and balance, here are good reasons to wait on buying a hybrid vehicle:
Hybrids cost more upfront
Sticker price along with taxes including sales and license fees tend to be 10-30% higher, usually about $3,000 or more. However, it is $1,500 between equivalent equipped Camry and Camry hybrids. How you recover this cost depends on several factors, including:
- Fuel cost
- Maintenance cost
- When you sell it
- Resale value
- Your income tax situation
- How much you drive
- Your insurance company
- The state you live in
- How you finance your vehicle
- Where you take it for service
- What type of warranties you bought
- Where you park and how you commute
A UC Davis study of hybrid consumers showed that none calculated these economic variables [refrence needed]. This seems to be no different than the reasons other cars a bought, but it could make sense to investigate if you can park for free in public parking or if you qualify for a tax rebate on the purchase of a new Hybrid as well as investigate if you can qualify for Solo-driving car pool lane stickers [only the most efficient vehicles qualify for this]. Omninerd has developed an incredibly detailed look at the economics of hybrid dated from 2005. 
Note that steeply rising crude oil prices are reflected in gasoline price increases and this can drastically shorten the period to break even on the investment to buy a Hybrid vehicle.
Other things to keep in mind about Hybrid electric vehicles are that they do not use components that are often the reason for breakdowns and early replacements, such as a starter motor and solenoid, an alternator, a clutch and several other parts. Also the regenerative breaking can reduce wear on the brake calipers and many Hybrid vehicles still have their original OEM brakes without ever needing replacement due to this, even after 6 or more years of operation and more than 100,000 miles. Also the 12V battery is not used to start the engine, so the life of this battery is longer due to the lower demands on its capacity. These and mnay other factors can contribute to lower maintenance costs and resulting faster break-even of a Hybrid car. There is of course the risk of a Hybrid vehicle component breakdown, which will need a dealer replacement because these are generally not available from third parties. Only Ebay can be a source of (used) replacement components as well as the new company 625k which aims to keep Hybrids on the road for 625k miles (1 million km) by providing an alternative source of spare or refurbished parts.
Globally there are about 50 electric, Hybrid and alternative fuel vehicles. Though more and more auto manufacturers are creating hybrids, there are more flexible fuel vehicles on American roads in terms of units. Hybrids are being tested in every segment from sub-compacts to SUVs. Strides are being taken and now, auto consumers can even choose between a durable Ford Escape Hybrid SUV or a luxurious Lexus GS 450h. So far, smaller commuting vehicles like the Civic and Prius have outsold all the rest. On the other side, Honda had to cut back production of the Accord Hybrid and Toyota did the same with the Highlander Hybrid.
Future choices will include plug-ins and higher mileage hybrids. Toyota is already working on a 94 mpg next gen Prius and plug ins have already topped 100 mpgs. These make more sense if you charge via solar or wind or at night when the grid is underutilized because the grid does not have any batteries.
Whether you wait to buy a future car with better gas mileage or start saving fuel and cost with a vehicle that is available today is a choice each buyer has to make for him or herself.
Although hybrids can be made to run on any fuel, most hybrids on the market today rely on gasoline, for which there is no synthetic substitute. Most diesel engines can run on bio-diesel without modification, although oil is used extensively in the growing, refining, and delivery of bio-diesel-- such that net oil savings are not as big as would appear at first sight.
The benefit of Hybrids is that use the same infrastructure of cars, roads, gas stations, service centers and so on, while reducing the consumption of crude oil by up to 50% which will make any country importing oil less dependent on the availability of oil from foreign sources. The available oil will also go a longer way in providing the energy we need for our daily life, we have more time to find alternatives. Some sources suggest that "Peak Oil" is already behind us because the production of oil has not grown world-wide for 2 years, indicating that the existing oil fields cannot produce more and new oil fields are in short supply. Any help to reduce oil consumption is therefor a good idea as there will likely be a crunch for the available oil, leading to extreme price increases, which seems to be what the crude oil price has starting to show.
Car battery disposal
All cars have batteries, hybrids have two. Car battery disposal is an issue for hybrids, when they are recycled, as the propulsion battery's useful life is specified to be longer than the life of the car.
The 12V batteries in most vehicles are highly recyclable since the infrastructure is already in place, unlike the newer batteries used in hybrids. So far, not enough batteries have failed to require a disposal infrastructure and many salvage batteries are selling on Ebay for plug-in projects. It is not likely that the propulsion batteries will end up in a landfill, because Toyota for example is offering a $200 bonus for every battery returned. In addition, unlike the 12V battery which contains the heavy (toxic) metal lead, the propulsion battery is constructed using NickelMetalHydride which has very little toxic metals and would not be a problem in a landfill, otherwise all the camera and other rechargeable batteries would have been an issue already. However, the Nickel is a valuable metal, so that is the reason it is being recycled.
Extra weight might impact performance in terms of acceleration except at low speeds where the electric motor torque gives excellent acceleration. Heavy cars require more energy to move, affecting safety and handling. This suggests that it is a good idea to buy a light car in order to get the best fuel efficiency. The Camry hybrid is about 300lbs heavier than the Camry XLE counterpart. The addition of an electrical engine in the front of the car and a battery pack in the rear behind the passenger seat increases the polar momentum of the car compared to the XLE, which can affect the handling of the car, this may be noticable in adverse weather conditions. The addition of extra torque and excellent control of the electric motor can be a benefit in other situations.
Low traction, high treadwear tires
The factory tires used on hybrids, specifically the Prius' Goodyear Integrity contribute to higher fuel economy and EPA test numbers but low real world stopping performance. The tires give better mileage due to a harder compound and tread pattern but poor traction, poor straight line stability, and were the lowest rated wet performance tire on tirerack.com.The Prius's panic braking was called "jerky and slightly odd" and straight line performance as "blown around in the wind" *Here are links to reviews of the prius's poor traction and straight line performance:  
Real world mileage
The observed mileage is lower than the EPA estimates when not driving EPA profiles. Note that this is true of all vehicles because of the ultimate testing conditions. The gap is even higher in Japan where the Prius and Insight are rated at 90-100 mpgs due to the specific profile used for testing fuel consumption. Recent studies in the U.S. have put hybrids in "real world" driving conditions, which shows the actual MPG for many hybrids. This is the data you should use to calculate your savings from buying a hybrid, so you avoid surprises. If you drive your car carefully, it may be possible to meet and even exceed EPA mileage estimates, many so-called Hypermilers show that EPA can be called conservative, but the average driver is driving far more agressively and this reflects in lower numbers for all vehicles, not just Hybrids.
Note that keeping the car well tuned will allow you to benefit from maximum performance and miles per gallon.
A well-refuted study by an auto industry analyst claims that it takes more energy to manufacture a hybrid than a regular car. The study claims the energy consumed by a Hummer is less than a Prius over their entire lives (due to higher design and manufacturing energy costs for the Prius and a shorter projected life span). The study, of course, has been attacked by environmentalists and those who read the Dept. of Energy fleet report, INL/CON-05-00964, where the first generation hybrids went over 160,000 miles with no appreciable loss of performance. But this study raises interesting questions if you like to consider ridiculous assumptions, such as how all SUVs got unusually high lifetime mileage. Another flaw from the study is that it charges the design and manufacturing costs to a car, while it is claiming to compare energy expressed in cost, so it makes the illogical choice to consider design (thinking) and being payed for that activity equal to buying and burning energy, which makes no sense.
- Here is a link to a summary of the study's findings:.
- The original study is available from CNW Marketing at: .
- A critique of the study is at GreenHybrid.
A white paper written by the founders of Tesla Motors, showed that hybrids ranked quite high in efficiency. Electric cars ranked highest, and the study can be found at Tesla's website.
Alternatives are available now including electric vehicles that PG&E gives a price break on electricity for, natural gas cars like Honda's HX that are cleaner and can be filled at home, sugar based cars that run on E85 and the like, prototype fuel cell vehicles, and/or any combination of above in hybrid form.
Also, the next generation of diesel cars optimized to run on ultra low sulfur diesel fuel will be available in 2008. These get equivalent mileage to hybrids without the added cost for the hybrid feature. They also emit about the same amount of carbon as hybrids. These next gen diesels use a nitrogen oxide storage catalyst controlled by the engine management system to treat the NOx and then a particulate filter downstream in the exhaust to further treat particulate emissions. The 2008 next gen VW TDI also meets California's Low-Emission Vehicle II standard and Federal Tier 2/Bin 5 standards.