Comparison
SL 63 vs SL 55 vs AMG GT 43: Three AMGs, One of Them Ours
Three cars, one badge, and a comparison that is usually run between the wrong two of them. The SL 55 and the SL 63 differ by 108 horsepower; the four-door GT 43 differs by an entire body.
Start with the honest part, because it changes how you should read the rest. Neither SL is in this garage. They are here as the cars people are actually comparing when they type these names, and we can put a specification against them and an argument around them. The car with a key on our board is the third one: the four-door AMG GT 43, in satin blue, with a fixed rear wing and four exhaust tips.
That is worth saying at the top because most pages on this subject are quietly selling one thing while describing another. What follows is the specification nobody publishes, the difference that actually decides it, and a verdict rather than a shrug.
All three on one screen
| SL 55 | SL 63 | AMG GT 43 | |
|---|---|---|---|
| Body | 2-door convertible | 2-door convertible | 4-door fastback |
| Roof | Fabric, folding | Fabric, folding | Fixed |
| Engine | 4.0L twin-turbo V8 | 4.0L twin-turbo V8 | 3.0L turbo inline-6, EQ Boost |
| Horsepower | 469 | 577 | 362 |
| Transmission | 9-speed automatic | 9-speed automatic | 9-speed automatic |
| Seats | 2+2 | 2+2 | 5 |
| Rear seats usable | For a bag | For a bag | For adults |
| Boot | 4–8 cu ft | 4–8 cu ft | Liftback, seats fold |
| 0–60 mph, tested | Not published | 3.0s | 4.8s |
| In our garage | No | No | Yes |
Two rows do most of the work here and neither of them is horsepower. Rear seats usable and boot are the rows that decide which of these cars fits a real weekend, and they are the rows the comparisons that rank for this question leave out entirely.
SL 55 against SL 63: what 108 horsepower buys
This is a smaller question than the search volume behind it suggests, and pretending otherwise is how a comparison ends up saying nothing. The two cars share a body, a roof mechanism, a cabin, a nine-speed gearbox and the same 4.0-litre twin-turbo V8. All-wheel drive and four-wheel steering are standard on both. What separates them is a state of tune: 469 horsepower against 577, from an engine Car and Driver's SL-class specifications note is borrowed wholesale from the AMG GT sports car.
The tested numbers make the point better than any adjective. Car and Driver has run the SL 63 to 60 mph in 3.0 seconds, and the four-cylinder SL 43 at the bottom of the range in 4.5. The SL 55 sits between them and exactly where is the least useful fact on this page, because there is no road in Los Angeles County where the difference is retrievable. Between the 405 at any hour and a canyon road with a blind crest every four hundred yards, you will use the top third of an SL 63's power for perhaps two seconds a day.
So the honest version of SL 55 versus SL 63 is: they are the same car, one of them is angrier, and if you are choosing between them on paper you are choosing on the wrong axis. The axis that matters is the next section.
The roof is the whole car, and it costs you the boot
Every SL is a folding-fabric-roof convertible with a pair of rear seats behind the front ones. That second row is not a second row in any sense you would recognise: Car and Driver describes seats with upright backrests that are too small for people and useful mainly for putting a bag on. The boot is worse. Rated at four to eight cubic feet depending on where the roof is stowed, it swallowed exactly two carry-on bags in their testing.
We do not keep an SL, but we keep four folding-roof cars, and the pattern is identical on every one of them: the roof lives in the boot, and the boot is where your luggage was going to go. On a Dawn it is an inconvenience because the car is enormous. On something the size of an SL it is a planning problem. Two people, two carry-ons, a weekend in Santa Barbara, and that is the ceiling.
What you buy in exchange is the only thing a roadster sells and the reason this body has survived seventy years: the roof comes down. Mercedes-Benz USA's SL roadster page carries the current US specification if you want the rest of it. In this city, on the coast road at five in the afternoon, that trade is a fair one — and it is a trade, which is what the pages ranking above this one decline to say.
GT 43: the AMG with back doors
The third car is the one nobody puts in this comparison, and it is the one most people asking the question should end up in. The AMG GT 43 is a four-door fastback on the same family of underpinnings as the big AMG saloons: a three-litre turbocharged straight-six with a 48-volt starter-generator, 362 horsepower, 4.8 seconds to 60 mph, and a governed 174 mph that nobody will ever see.
On paper it gives away 215 horsepower to an SL 63 and looks like the sensible choice. In practice it is not the sensible choice at all, because the straight-six is the smoothest engine of the three and the body is the most dramatic. Ours is finished in satin blue with a fixed rear wing, and it gets photographed on Sunset more than cars twice its rate. The roofline is low enough that people read it as a coupe until they see the rear door handles.
The part that actually decides it: five seats and a liftback. The rear seats are for adults rather than for a briefcase, they fold, and the tailgate opens over a boot in a completely different category from anything with a folding roof. Four people and their luggage to Palm Springs is a normal Friday in the GT 43 and an impossibility in either SL.
The trade-off, and it is a real one: it sits low. Steep Hills driveways and the ramp at some Downtown garages want a slow, angled approach. Ask about the specific address if you are unsure — we would rather tell you before the day than have you discover it at the kerb.
Three AMGs, three jobs
Read the right-hand column first. Two of these answers are cars we are describing; the rest have keys on our board.
| If the brief is… | The answer | Why | Where it is |
|---|---|---|---|
| Two people, coast road, roof down | SL 55 | The roof is the product and the extra power is not | Comparison car |
| Two people, and the loudest V8 in the range | SL 63 | Same car, angrier engine, same tiny boot | Comparison car |
| Four adults and a weekend of bags | AMG GT 43 | Five seats and a tailgate; no SL can do this at all | In our garage |
| An arrival where the car is photographed | AMG GT 43 | The fastback profile does more standing still than a soft top does | In our garage |
| The AMG shape with a high seat | AMG GLE 53 | Same rate, same six-cylinder family, an SUV instead | In our garage |
The verdict, since somebody has to give one
Between the two roadsters there is no case for the SL 63 over the SL 55. The 108 horsepower above it buys a figure you will quote and a difference you will not feel, and both cars carry the same two carry-on bags to the same places. Between the roadsters and the four-door, the GT 43 wins unless the roof coming down is non-negotiable — five seats, a folding rear bench, a tailgate, and the only one of the three you can put a date against here.
What actually wears an AMG badge in this garage
Two cars, at the same rate, and they are nothing alike. The AMG GT 43 and the AMG GLE 53 both sit at $229/day, both run a three-litre straight-six with EQ Boost, and one of them is a low four-door fastback while the other is a coupe-roofed SUV that makes 429 horsepower and stands a foot taller. Choose on height and luggage, not on the badge.
Above them is the AMG G 63, which is a different conversation entirely and has its own page on what a G-Wagon costs. And if the AMG badge is not the actual requirement — if the requirement is a Mercedes for a week in Los Angeles — the whole range from the CLA 250 upwards is laid out in which Mercedes to book.
What sits outside the day rate
The rate is the car for twenty-four hours. Four things sit beside it and all four are in the quote before you pay: a refundable security deposit, which is held rather than charged and comes back 5–7 business days after the car does; mandatory damage-and-liability cover, priced per day by the car's deposit band; Los Angeles County sales tax at 9.75%; and delivery, if you want the car somewhere we do not already go.
Under twenty-five there is a young-driver fee: $50/day on cars in the standard deposit bands, which is where the GT 43 sits, rising to $175/day once a car's deposit reaches $1,500 or more. Collection from Robertson costs nothing and delivery to our partner hotels in Beverly Hills is complimentary. The airport is priced separately — $75 each way leaves the car in the parking structure for you to shuttle out to, $150 each way brings it to the terminal. On a low four-door with a liftback, the parking-structure tier is perfectly workable; it is the cars with no boot where it stops being.
Cancellation terms and the rest of the small print live in the terms and conditions, which is the only place they should live.
AMG GT 43
Four-door fastback · 362 hp · five seats
Live rate on its page →
AMG GLE 53
Coupe-roof SUV · 429 hp · the tall one
Live rate on its page →
AMG G 63
Ladder frame · 577 hp · the loud box
Live rate on its page →
If the folding roof is the part you cannot give up, say so rather than settling for a fastback. We keep four convertibles and none of them is an AMG, but a roof that comes down on the coast road is a roof that comes down, and the boot problem is the same on all of them.
Every Mercedes in the fleet, with live rates →One of these three has a back seat, a boot and a date you can put against it.
Send the dates and we will confirm the GT 43 — and tell you honestly if the GLE 53 is the better car for what you have described.
See the AMG GT 43Cars in this guide
Keep reading
Frequently asked questions
What is the difference between the AMG SL 55 and the SL 63?
One number, and it is horsepower: 469 against 577, from the same 4.0-litre twin-turbo V8. Both use a nine-speed automatic, both have all-wheel drive and four-wheel steering as standard, and both have the same folding fabric roof, the same pair of token rear seats and the same very small boot. On a Los Angeles road the difference between them is a thing you quote rather than a thing you feel.
Is the AMG GT 43 slower than an SL 63?
Yes, and by a wide margin on paper. The GT 43 makes 362 horsepower from a three-litre straight-six and reaches 60 mph in 4.8 seconds; Car and Driver has tested the SL 63 at 3.0 seconds. What the GT 43 has instead is four doors, five seats, a liftback tailgate and rear seats that fold — none of which any SL offers at any price.
Which AMG can I actually rent in Los Angeles?
The four-door AMG GT 43 in satin blue, the AMG GLE 53 in black, and the AMG G 63. The GT 43 and the GLE 53 sit at the same daily rate and share the same three-litre straight-six family, so the choice between those two is about height and luggage rather than performance.
Does the AMG GT 43 fit four adults and luggage?
Comfortably. It is a five-seat fastback with a liftback tailgate and folding rear seats, which is the whole reason it belongs in this comparison. The one thing to check is ground clearance rather than space: it sits low, so a steep driveway in the Hills or a sharp garage ramp wants a slow, angled approach.
What does an AMG rental cost on top of the daily rate?
A refundable deposit that comes back 5–7 business days after the car does, mandatory damage-and-liability cover priced per day by that deposit band, Los Angeles County sales tax at 9.75%, and delivery if you want the car somewhere we do not already go. Under twenty-five a young-driver fee applies: $50/day on the GT 43's deposit band, and $175/day on cars with deposits of $1,500 or more.