Home    Search    Gallery    How-To    Books    Links    Workshops    About    Contact

BMW 540i M-Sport vs. Mercedes SL500

2003 BMW 540i Sport

1997 Mercedes SL500


Here's a comparison between my 2003 BMW 540i M-Sport automatic and my 1997 Mercedes SL500. Click each of those links or the photos above to see explicit details on each.

See also my comparison between the Mercedes E500 and the BMW 540i.

On paper they are very similar. They're both two-ton rear-wheel-drive independent suspension German cars with a 300 HP 4-valve V-8s sucking premium gas with a 5-speed automatic transmission with the same gear ratios! They both have dash-mounted MPG gauges and trunk-mounted batteries for perfect weight distribution. One, the SL500, has about 10% more displacement and power and also weighs about 10% more, so it's almost a wash. The power-to-weight ratio of the BMW 540 is within 1% of the Mercedes SL500: 13.10 vs. 13.22 lbs/hp. Each gets to 60 MPH in just over 6 seconds and hits the quarter in under 15 seconds, limited mostly by traction. They both have 155 MPH-limited top speeds and twin latches holding their hoods closed for the Autobahn.

They both mount their batteries on the lower right side of the trunk and have six-disc CD changers mounted in the same orientation on the left of the trunk. The CD changers both take the same Alpine magazine!

The big differences are the rear axle ratios, sport packages, body styles and dealer support.

If it's a nice day take the SL500. If your roof is up take the 540i.

There are two completely different versions of the 540i: the regular one, and the $4,100 sport package. I'm talking about the sport version, which is completely different than the standard 540i. The standard 540i is very similar to the SL500 while the 540i Sport is barely street legal. The Sport package replaces most of the drivetrain and suspension with different components.

The sport and non-sport versions of the SL are just different trim and tires. They drive and feel the same as each other.


The SL500 is a silky smooth, silent and extraordinarily powerful and luxurious convertible. Driving the SL500 you are a Deity floating over the Earth freed from its cares and issues of space and time. The BMW 540i Sport feels like a solid brick of hard rubber that connects you directly to the road with nimble, agile and responsive handling unlike any other sedan you've ever driven. The BMW 540i Sport makes you laugh and hoot out of pure fun, the SL500 is more elevating and relaxing and has omnipotent power. It's appropriate that the SL500 is white like a Heavenly cloud and the 540i is dark and sinister. The 540i is fun to drive to the point of selling your soul to the Devil, the SL500 makes any drive Heaven.

The SL500 (1997) is a velvety smooth, quiet, comfortable, heavy and very powerful convertible. I've also always had remarkable service from Mercedes dealers and their lifetime roadside assistance. It's always a pleasure dealing with Mercedes.

The Mercedes SL500 is a 5.0L V8. It also comes as an I-6, the SL320, and as a V12, the SL600. SL500s come only with automatic transmissions in the USA. This R129 body style was made for model years 1990 through 2002. I'll explain year-to-year variations below and I cover them in explicit detail on this page here.

The BMW 540i M-Sport is a taut, agile and responsive sports car that's also heavy, quiet and comfy. So far the dealer from whom I purchased my 540 sport has made me realize why surveys show most people would prefer to go to the dentist than visit a car dealer. I trust this will improve when I use another dealer for service.

The BMW 540 is a 4.4L V8. The sport and non-sport versions are very different. I'm talking only about the special Sport model here. It also comes with standard transmission and as I-6, Diesel and station wagon versions. This E39 body style was made for model years 1997 through 2003. I detail the variations of the 5-series here and the explicit details of the sport package on my BMW 540 page.

Turn the wheel in the BMW and you change direction much more quickly then the Mercedes. The BMW is as fun and zippy as a Miata or SLK; the Mercedes is a quiet cruiser much less suited for autocross.

Each of them flies about as hard when you hammer it. Each shifts down to the lowest available gear and takes off. The BMW 540i M-Sport has a tighter suspension, lower profile tires and much lower gearing than the SL500. Thus you can easily pull burnouts just by hammering the 540 from a stop while the SL500 hooks up and takes off. Of course the traction control of the 540 comes into play when you launch the 540 because of the low gears. The SL500 is ideally geared for standard tires. The BMW 540 Sport is geared to hook up with some sticky warm drag slicks.


My 2003 BMW 540 is an M-sport, auto transmission, 290 HP version. In 2003 the sport model got the M suspension, door sill badges and tires as incentive to buy the last of the previous model 5-series. The non-sport models I drove were nowhere near as fun, and as we know the new 5-series is designed more for people whose main concern is the cupholders. My BMW 540 zips around as nimbly as a Miata or Z4 or SLK and hauls Holy ass on top of it. Non-sport versions weren't impressive. I drive for fun, not transportation.

I don't yet go into explicit detail from year to year. The 540 Sport is fairly similar from 1997 - 2002 with extra insanity added in 2003. Power was 282 HP through 2001 and increased to 290 HP for 2002 and 2003.

I outline the various other 5-series models here. It also comes as a several inline six-cylinder versions: the 520, 525, 528 and 530. It also comes as a station wagon, the 540iT as well as a 6-cylinder wagon and even Diesel sedans and wagons. Standard and automatic transmissions are available. Of course if you want the standard shift you'd be better off with the M5 and not stopping at the 540. My girlie wife insisted on the automatic.

SPECIFICS: Mercedes SL500 (R129)


I have a huge page with the historical details here. I've extracted the basics below.

This comparison is using my 1997 SL500.




The SL500 rides like a Cadillac. That means soft and smooth, not zippy. It's a unibody convertible, so it's very good, but still can get a bit floppy as you drive. It's better with the standard hard top attached, but that sort of defeats the purpose of a convertible. The engine is smooth and powerful and efficient. Powertrain and brakes are wonderful. The driving experience includes things like support and the dealer network, which are extraordinary. You know they're there to help if you ever need it.

I had TWO flats the same weekend in 2004 when I only had 18,000 miles on it. The valve stems had aged because the tire place had fogotten to change them when they changed the tires. In the desert at 104 F they cracked and died. Obviously I only had one spare. MBZ roadside help did the research and directed me to a facility out in the desert on a Sunday afternoon that was both open and could service my tire. A Lexus would have expired the roadside help; you get it for life with Mercedes.

The pleasure factor comes mostly from having unlimited silent power and the satisfaction of being in a classic that was designed and manufactured with no compromises and an excellent hi-fi system. It has a big trunk and is so practical you can do just about anything in it.

The gearing is optimal: 1st gear is just on the verge of breakaway with the tires, and if you only put H rated's on it you'll be spinning against the traction control on takeoff. Likewise top gear is an overdrive for economy. You turn 1800 RPM @ 60 MPH. The gauges are right on, the speedo is accurate to within a fraction of a MPH. The hi-fi is extraordinary and every model of SL500 comes with it; it was not an option. Thus you put on your favorite music and head out for fun and relaxation. It's not the car for autocross or twisty mountain roads; it's for traveling fast in grand style.

BMW 540

The 2003 BMW 540 M-Sport is an entirely different story. My first reaction, due to the low gears and huge engine and tight suspension is something like "Holy cow, these guys are NUTS!!! This car is sick!" I had to learn not to chirp the tires backing into my garage! It's just like the good old days of 4.11 gears from Detroit: the low 3.15 gearing of the sport model lets you shred tires with just the throttle. Top gear isn't an overdrive: you pull 2100 RPM at 60 MPH or 155 MPH at redline. It's also nimble and agile; nothing like Detroit in the 60s. It's a hoot to jump in and run around the block, and the very first day I had the neighbors were yelling at me for turning donuts in our cul de sac. Sorry. The transmission is always turning a lot of RPMs and sucks gas; the SL500 at part throttle drops you down to 1200 - 1500 RPM at around town speeds; the 540 always seems to think you're in a race and keeps you around 2000 - 2500 RPM even at light throttle. I haven't even moved the dopey steptronic selector to the left for the sport mode yet. Fun, but wasteful, and exactly why I got it. I get 11 MPG running errands, daintily. I would have gotten something with a blower if I could have so I don't fret the gas sucking.

Sport Packages: a key to the differences

The sport package of the SL500, which I didn't order, is just trim and lower profile tires and wheels. The transmission, rear axle and probably the suspension is unchanged.

By comparison the sport package of the BMW 540i is hard-core. The 540's sport package includes the tire and trim options of the SL500, and more importantly a high-stall torque converter, different suspension, different transmission, and very importantly, a much lower axle ratio.

Transmissions, Ratios and Axles

They are both electronically controlled 5-speeds with almost the exact same ratios! The Mercedes adds a second reverse gear for winter or evasive high-speed reverse driving.

ratio : 1 BMW 540i SL 500
Reverse II
Rear Axle
Tire Revs/mi
RPM @ 60 MPH    

As you can see the axles and tires are what differentiate the two. The BMW 540i Sport is geared much lower. The 540i Sport's top gear is the same as the SL500's 4th. The non-sport 540 is similar to the SL500.


When the top's down you're The King in the Mercedes. I love convertibles and prefer even a VW Rabbit convertible to just about anything with a roof. I love the wind and the sky, even at night or when it starts getting cold or hot. The SL500 has magnificently powerful heating and air conditioning and makes almost any conditions comfortable. Mine also has the optional seat heaters which are great for use at night.

If the top's up then the BMW is much more fun because of its nimbleness and agility. The BMW 540i Sport is simply insane in it's handling and overall character. With the top up the SL500 is more like any other powerful luxury car.


The leather of the BMW feels like a soft glove. The leather of the Mercedes is much stiffer. Both seats are as firm as we expect in German cars.

I put sheepskins in my Mercedes and they feel great. I run my BMW naked.

Hi-Fi System

All SL500s since about 1993 have an extraordinary Bose system.

The standard radio on the 540 sounds like just a radio. You need to order the premium hi-fi system for about $1,800 to get a system which is similar to the SL500. Of course in Germany you drive with the radio off and it's only for speech anyway, not music. Forget the tinny standard system for music; I'm discussing the premium system. The premium BMW system is identified by the "DSP" marking on the radio. DSP itself is just a gimmicky echo chamber. Don't activate it, but it does tell you the premium speakers and amplifiers are hidden under the plain grills.


The BMW has pleasantly neutral voicing, perfect for just about anything.

The Mercedes has more presence, appropriate for driving with the top down.

Both systems sound great without any adjustment of the tone controls.

Level Control with Speed

The Mercedes gets louder as you drive faster. I wish the amount by which it got louder was more pronounced because I always drive with the top down. The level seems to jump up a little in steps right around 45 MPH and then again around 70 MPH. It has a little bit of hysteresis and then makes slight steps as you slow down. You'd never notice unless you listen for it.

The BMW not only does that, it allows you to set the amount by which the level increases as you go faster! The BMW makes its level changes smoothly, with a time constant and delay of about a second. Again, you won't notice this unless you listen for it. When set correctly (see your owners' manual) you won't notice it at all: all you'll notice is that you never have to turn the music up or down as you drive.


The good BMW system has somewhat more extended bass with less resonance than the Mercedes, as you'd expect from having the volume of the trunk to use for Vab.

The Mercedes' subwoofer is right behind the driver's seat, so the driver feels the bass. It's a bit more boomy since it's a double-bandpass system in a small box.

The BMW system uses an Nokia subwoofer system in a slim enclosure attached under the back deck.

Both systems deliver mountains of strong, solid bass. The SL500 is more thumpy and the BMW is better if you play bass as I do and actually want to hear each note have its own pitch. The SL500 is perfectly designed for use in a convertible, likewise, the BMW is perfect for use in a sealed car.

Traction Control Systems

They are both excellent. They work smoothly and confidently let you do things you probably shouldn't be doing. Unlike lesser cars, you can just hammer the throttle while doing silly things like hard cornering and they gently bring you back in line.

The biggest difference is the warning light that comes on to let you know you're getting close to the limit.

The light on the BMW 540i, called DSC, is at the bottom of the dashboard so you often don't see it, since it usually comes on while cornering. The SL500 is much better since the light, called ESP or ASR in Mercedes, is at the top inside of the speedometer where you can see it with the wheel turned.


The Mercedes speedometer is dead on. The BMW overestimates your speed by about 7% or 4 MPH at 60 MPH. Thus you can go faster in Mercedes if you travel based on indicated, and not true, ground speeds.


The Mercedes has a real clock with hands. It clicks ahead by one minute each minute. Unfortunately the steering wheel usually blocks it, a rare ergonomic faux-pas by Mercedes.

The BMW only has a digital clock, and worse, this digital clock doesn't always have the same location on the dash, if at all. You can program the BMW's computers to have the clock in the radio and/or right above the steering wheel, or to vanish entirely. I prefer a clock in a fixed location.

Neither is particularly accurate. Both run fast. By comparison the chronometer in my 1988 Mercedes 190D was so accurate I detected no variation even after six months before adjusting for daylight savings time.


The BMW 540i has a complex digital navigation (time/speed/distance, not GPS), trip and fuel computer, standard. The Mercedes SL500 only has a trip odometer. The BMW computer is covered in depth here. The Mercedes has no computer to distract you from driving.

The Mercedes MPG gauge appears just to be a simple vacuum gauge. The BMW 540's MPG gauge is a true electronic calculation performed many times per second and is accurate. The Mercedes gauge almost always gives meaningful readings without being pegged. The BMW gauge stops at 8 MPG so it's usually pegged anytime you're accelerating. I'll declare this one a toss up.

Warning Lights

Placement and Prove-Out

All cars test their warning lights for a second when you turn on the key. You are supposed to look for dead lights each time your car is started. This way you'll know to replace any dead bulbs or circuits before you have a problem about which the light was trying to warn you. In the old days smart people looked to see that the oil pressure bulb was OK and that was about it.

The SL500, like all 1980s and 1990s Mercedes, has all the warning lights in a single row along the bottom of the dash. This makes it obvious if any of them isn't working each time you turn on the key. They appear to be incandescent bulbs.

The BMW 540i, like most cars, sprinkles warning lights all over the dash. Therefore you have no idea if one is missing unless you really look hard and have all their positions memorized.They appear to be LEDs.

High Beams

The blue warning light is top center on the BMW 540i dash, so it's obvious if you forget to dip your beams with oncoming traffic. It's dim enough not to annoy while driving in dark places.

The SL500's high beam dash light is on the far left, which for me partially hides it behind the cruise control stalk. It's not at all annoying at night, but much less likely you'll realize your high beams are on if you forget.

Traction Control

The traction control warning lights tell you your tires are slipping. You see this light when you're driving like a nut and ought to slow down.

The SL500 puts this light front and center at the top of the speedometer, where you can see it even with the wheel turned. This is good, because yo most need to know this while turning.

The 540i puts it just above the steering wheel, so you'll never see it while turning, which is when you most need to see it for safely.

Interior Storage

The two-seat SL500 oddly has more interior storage than the BMW 540i. The SL500 has two automatically locking large center storage consoles, the 540i has only one tiny opening big enough for a bar of soap.

The SL500 has two automatically locking rear storage areas, the BMW has none.

The BMW has a conventional glove box; the SL500 instead has a smaller storage area in the center of the dash.

The SL500 has a huge, deep, secretly covered storage area in each door. The 540i has conventional pockets in each door.


The Mercedes rides better for your passenger than the BMW's near-racing suspension. The SL500 is great even for 500 mile-a-day trips. I haven't driven the BMW enough to find out.

The gearing is different between the two. The taller gearing of the SL500 (as well as a Winter mode) makes it easy to drive smoothly.

The low gears of the 540i sport make it difficult to take off gently. Even a mild tap of the throttle sends you flying.

This of course compares the Sport model 540i. The standard model 540i is probably pretty similar to the SL500.

Next: Comparison between the Mercedes E500 and the BMW 540i.


Back to Top of page

Back to Mercedes SL500 page

Back to BMW 540i Sport page

Home    Gallery    How-To    Books    Links    Workshops    About    Contact