Thanks to some crafty engineering, you may never have to experience
“Shift Shock” again. Here’s how a CVT delivers that smooth driving
experience.
HOW IT WORKS
Imagine
the CVT like a bicycle’s gear system. It’s made up of a pulley system,
with cones at each pulley, all connected by a chain belt. These cones
move closer together or further apart to increase or decrease the
diameter at which the belt operates. The ratio here is important, and is
selected automatically based on factors like gas pedal position,
vehicle speed and engine speed.
What all this means is that a CVT
doesn’t shift at all like a traditional gearbox. The ratios are always
changing in order to find the perfect combination for speed, fuel
efficiency or both. Some CVTs even come with buttons to help shift
between pre-set ratios which helps mimic a traditional automatic.
The
first time you drive a car with a CVT, you’ll know.
The feel of a CVT can be odd. The rpm of the engine can fluctuate a
lot while driving, especially when accelerating. Or when accelerating
hard, they’ll just sit unchanged at a lofty rpm level while the car
pulls forward.
Compared to an automatic or manual transmission, a CVT
is much smoother. Feeling like one really long gear, in reality its a
nearly infinite collection of gears all meshed together.
CLEAR BENEFITS
Many cars nowadays are being sold with CVTs instead of traditional
automatics, mainly because of their efficiency. In fact, the new 2013 Nissan Altima (above, read our review here)
uses a CVT transmission and is rated as the most fuel efficient
mid-size sedan on the market with a 38 mpg highway rating. In addition,
almost all hybrids use CVT transmissions, including the Prius, helping
maximize fuel economy.
While
drawbacks in terms of responsiveness are usually noted by driving
“enthusiasts”, Continuously Variable Transmissions have one key
advantage over their automatic and manual counterparts. When driving up
hills, where traditional automatics can struggle, a CVT can seamlessly
provide power without shifting. Even-speed hill driving can prove to be a
tough endeavour for novice manual transmission drivers. We actually
praised the CVT in the Scion iQ (read our review here)
for delivering exactly this sort of responsiveness on the hills in San
Francisco, despite a tiny 1.3-liter engine and just 94 hp.
Nissan has
been selling cars with CVTs for quite some time now, and has had
considerable success introducing the new transmission type into the
market.
According to Steve Yaeger, from Nissan North America, “With coming
CAFE and CO2 emissions regulations requiring better fuel economy and
lower emissions, the CVT gives the Nissan lineup an attractive
alternative to conventional automatics that is more efficient on both
fronts.”
NOISY, AND WHAT ABOUT RELIABILITY?
Still, CVTs are having a tough time breaking into the market. It
turns out that many drivers don’t like the loud and strange noise of
their car’s engine revving wildly. Many drivers liken the sound, and the
feeling, to that of a slipping clutch. Additionally, CVTs are usually
less likely to be paired with higher horsepower, or higher torque
engines.
Lastly, not all CVTs are well equipped to deal with towing.
Additionally, the reliability of the modern CVT has yet to be tested.
The Nissan Murano (seen above) was the first car Nissan offered with
only a CVT, and it had some pretty serious problems. Some were so bad
that the whole transmission had to be replaced.
However, since then, Nissan has extended the warranty of the
transmission to 10 years/120,000 miles. That should help alleviate any
fear buyers may have over the reliability of getting a car with a CVT.
If you enjoy revving your car to its redline, and feeling the thrust
as your car shifts, then maybe a CVT isn’t for you at all. For those
types, you may want to try your hand at a Dual Clutch Transmission
(DCT) if you want to have a sporty feel and keep an automatic.
Otherwise, the CVT is a fine choice in the world of economical cars.
Many hybrid vehicles use a form of CVT to get such high mile per gallon
numbers. It’s good with fuel, and smooth. Sorry about the noise though,
but you might just get used to it.
KNOW WHAT YOU WANT
In summary, there are a few advantages to getting a vehicle with a
CVT: It’s good on gas, gives a relatively smooth ride, and is versatile
enough for daily driving. It also has a few drawbacks. It’s nowhere near
as fun or engaging as a dual clutch automatic or manual transmission.
It can also make quite a racket when accelerating hard. Keep these
points in mind when looking at your next car. A CVT can help make or
break the purchase, so be sure to know what you want, and how the
transmission plays a part in it.
Source : http://www.autoguide.com/auto-news/2012/05/should-you-buy-a-car-with-a-cvt-transmission.html
No comments:
Post a Comment