blueSL

Autocar didn't publish my letter telling them I thought their review of the SL55 was garbage, no surprise there.

At the time, I did express surprise at the 0-100 time of 11.2 seconds. This week, they're claiming that the 155mph/250kph limit restricts performance even below that limit and that removing both lifts the top speed and improves the 0-100mph time.

They're saying the SL55s they've tested are restricted and are slower ("disappointing") compared to the car auto motor und sport tested. They also say that MB engineers say that removing the speed limit allows them to deploy more torque at lower speeds. Sounds like BS to me but perhaps one of you guys would like to comment, especially if you have had the limiter removed.

Richard, what do you think?

Next week, they are doing comparative 0-100-0 times for a bunch of cars, inclluding the SL55 but it looks like this will include the 11.2 second car, so we should not be expecting miracles. However, for a car to do 0-62 in 4.7 seconds, 11.2 does sound a long time to get to 100. If you do the math, it's only 40% as accelerative from 62 - 100 as from 0 to 62. For a car which does 200mph?

Maybe the engines need to loosen up.

GMW

I assume you are talking about Autocars recent Drive report on the SL55 which was wasteful. They had 4.8 sec time of 0-60mph! ( yeah right) It even states 4.7sec 0-100km (0-62mph) in the brochure!!! and Mercedes is always conservative.

I saw the 11.2 time of 0-100 but something was off. Maybe they did that test right after running the car hard a couple of times around the track. The engine and supercharger would be quite hot and would add a second or two onto the numbers. You've also got other factors like the track temp at the time of test and humidity level. I assume that they used super premium fuel and correctly adjusted tire pressures. All these factors can add or subtract a second or two.

The limiter for 155 doesn't limit the accelartion performance unless you hit the limiter
Motortrend, who actually tested the vehicle, got the 1/4 mile in 12.55sec at 116.1mph
The limiter are only designed to ease off the power as you approach the set limit.

WyattEarp

Problem: you are using linear mathemathics to compare acceleration rates which are measured as distance over the square of time. Also drag resistance increases with the square of the speed. Aerodynamics play an important role over 60 mph.

blueSL

You're certainly correct that a car at 100 has 2.78 times the energy of one at 60 but in a 0 - 100 run, the bulk of the power from the engine goes in giving the car kinetic energy compared to slicing through the air.

Maybe the car's weight is counting against it but a number of 11.2 suggests the car will be outrun by the 575, Murcielago and 996T to 100mph, which seems to contradict the experiences of people who have driven the car, such as Lonman in the Gumball rally.

dNA3D

In fact, most of the energy from the torquey engine is used to get the 4,400 lbs of aluminium, but mostly steel moving at those low speeds. Only at speeds in excess of 150mph do aerodynamics start to affect the car more.

I've also seen the SL get from 0-60 in 4.32 seconds by Motortrend in their video review of the first SL to hit the USA.

Richard

If you read the smallprint in the article, it says the times have come from the manafacturer - which I assumed to mean that they never tested it at all. Which made the 0-60 in 4.8 figure look even stranger, since as you say the manafacturer says 0-100kmh (62.5mph) in 4.7 seconds ..

I await the group 0->100->0 tests :-)

Cheers
R