Multitronic CVT (was: return of the inline 5....)
ti at amb.org
Tue Jan 14 12:27:18 EST 2003
Kent McLean writes:
> Ti Kan wrote:
> >My newest -- an '03 A4 1.8T CVT is too new to have any history,
> So, do we get an owner's report of how the CVT works in real life?
> I'm looking ahead to the day I replace my 200. Far, far ahead.
It's quite unobtrusive. You drive it just like you do a slushbox,
except that you don't feel any shifts. The RPMs change and acceleration
occurs smoothly and seamlessly. Also, the CVT give nothing away to a
manual transmission with respect to fuel economy and performance.
Audi rates the 0-60 acceleration of the CVT car as identical to that
of a manual transmission. The 1.8T is an amazing little engine.
It has plenty of pep yet it also returns great gas mileage. I get an
average in the high 20s in mixed driving. Not bad for an engine making
170hp hauling a relatively porky chassis.
This is a really nice setup for congested traffic where repeated
shifting and clutchwork could get to be a chore. There is no torque
convertor in Audi's implementation. Instead, there is an electronically
controlled lockup clutch that gets you going from a stop. Hence there
is none of the power losses that are traditionally associated with
a torque convertor.
The CVT shift lever only has four positions P R N D. The ECU determines
the ratio based on your throttle and brake inputs, as well as engine
load and various other sensors. From the D position you can move the
lever to the side into a tiptronic-style shiftgate, with spring-loaded
+ and - positions to "upshift" and "downshift". In this mode, the
ECU simulates a 6-speed transmission, and the instrument cluster display
changes from "PRND" to "654321" to show which virtual "gear" you've
selected. It will automatically downshift for you if your speed drops
below an acceptable threshold for a chosen ratio, but will hold a
"gear" while you accelerate until you upshift. In my opinion, the
tiptronic-mode is kind of superfluous and nothing more than a play-
gadget to impress your friends. Unlike a slushbox, the CVT mode works
so well there is really no need for "manual override".
The only gripe I have about the car is the 4-cylinder sound of the 1.8T.
After becoming more accustomed to the aural delights of the V6 and I5
cars, the 1.8T just doesn't make the right noises, particularly when
revved high. The car is otherwise refined and quiet though.
My 4000 is also a 4-cylinder, but it has a custom aftermarket
exhaust so it sounds quite sporting. I think the 1.8T cars could
really benefit from some exhaust tuning, but then it might lose some
of its refinement.
2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
/// Ti Kan Vorsprung durch Technik
/// AMB Laboratories, Sunnyvale, CA. USA
/// ti at amb.org
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