OK - I assume you're talking about a Mk2 Punto. Just in addition to what Jon has said...
Do not top up with anything other than correct CVT oil - and for the Mk2, that is either the FIAT CVT-NG oil, or the Nissan NS-1 oil if you can't get the FIAT oil for some reason. The replacement interval for the oil and the filter is 40,000km (25,000 miles). The filter is special and expensive because it's a high-pressure type. But it's an easy job to change since it's screwed on to the top of the transmission casing (near the 'NISSAN' label
)
'L' engages an extra epicyclic gear (can hear a whining noise) and is not very useful for anything I can think of. Don't use it for engine braking - it's too low for that. When descending a steep hill, use the +/- ('manual') mode to select '4' or so - that should do it.
Don't bother with +/- at any other time. All it does is it introduces vague 'steps' into the shifting - no help to anything and the revs still vary up and down even when it's allegedly fixed into the selected ratio, mainly because of the torque converter (see below) so it's not really a 'manual' in the true sense - more like a manual with a slipping clutch!
'E', according to the supplement, "curtails emissions in exhaust". I think it's safe to assume that it is also an economy mode. It restricts the engine revs and allows high-geared 60mph cruising at about 2000RPM if you're very gentle on the throttle - a good feature of the CVT is the high ratios it gives. I have E on almost all of the time - I find it helps to turn it off if you're trying to overtake, or if you're having difficulty getting up a hill.
I know what you mean about the over-revving - there's an awful amount of 'slack' between throttle-off and throttle-on. Let's say you're rolling along at 20 mph. Foot-off, the revs drop to about 1200 RPM (or less). Foot-down, even moderately, and the revs flare up to about 2500 before there's any drive. That's because of the torque converter slippage - the Japanese contribution to the project that earlier FIAT CVTs (like Jon's Panda) did not have. You can't do anything about it and the only solution is to use the throttle lightly to minimise the power lost.
Strangely the opposite is true when starting off from a standing start. It takes several seconds for the revs to climb past 2000 so I find myself momentarily bogged-down in the middle of an intersection, roundabout etc. moving at a walking pace. In a manual transmission car the revs pick up quickly in 1st where the CVT lowest ratio feels more like 2nd in a manual. It's just something you have to allow for. Turning 'E' off gives you a bit of a high-revs boost later once you're moving, but doesn't help the starting-off.
I found that Wikipedia article a little silly when it reports "This can give a perception of low power, because many drivers expect a jerk when they begin to move the vehicle." I have a better measurement of "low power" - 0-60mph in my Punto Sporting with CVT takes around 16 seconds. 0-60mph in a manual-transmission Punto Sporting takes around 11 seconds. 0-60 in my other cars takes around 8 seconds, so my Punto feels super-slow
Something I find helpful with the CVT is to shift the lever into 'N' just before you come to a rest. This prevents a slight jerking as the belt makes its way up the pulley that's increasing in size (as the transmission moves to the low ratio). I talked to a specialist about this and again, there's no solution possible other than to allow it to adjust itself in neutral rather than in drive.
The Wikipedia article implies that CVT gives better fuel economy than a manual transmission, but I don't know of any real-life example of this (and, the article doesn't mention any).
For the Punto, the fluid coupling of the torque converter is what kills the economy compared with a manual transmission. I get from 9km/L (24mpg) average around town up to 18km/L (50.78mpg) driving gently (90km/h/56mph max) on a long trip.
A consolation prize is that the torque converter smooths out the drive compared with the magnetic powder clutch of the earlier FIAT CVT - and apparently, the torque converter is more reliable (being simple, old technology).
A manual transmission Sporting returns nearly 40mpg average around town(about a third less fuel used) and even my Uno Turbo manages 34mpg and has a lot more power. So for economy, as well as acceleration, the CVT is a bad choice. I wish I'd held out for a manual!
-Alex
