SL 63 vs SL 55 vs AMG GT 43: Three AMGs, and the One to Drive in LA
The SL 55 and the SL 63 are the same car with 108 horsepower between them: one body, one folding fabric roof, one cabin, one nine-speed gearbox and the same 4.0-litre twin-turbo V8 in two states of tune. The four-door AMG GT 43 is a different car entirely, with five seats, a liftback and rear seats that fold. Between the roadsters there is no case for the 63 over the 55 on a Los Angeles road; between the roadsters and the four-door, the GT 43 wins unless the roof coming down is non-negotiable. Neither SL is in this garage; the GT 43 is.
| What differs | Figure | What kind of number that is |
|---|---|---|
| Power | 469 / 577 / 362 hp | SL 55 / SL 63 / GT 43. The first two from one V8; the third from a turbo straight-six. |
| 0–60 mph | 3.0 s / 4.8 s | SL 63 / GT 43, as tested by Car and Driver. The SL 55’s figure sits between and is not published. |
| Seats | 2+2 / 2+2 / 5 | The SL’s rear pair is for a bag. The GT 43’s rear bench is for adults, and it folds. |
| Boot | 4–8 cu ft / liftback | Both SLs took two carry-on bags in testing. The GT 43’s tailgate opens over a different category of space. |
| Roof | fabric / fabric / fixed | The only thing the roadsters sell, and the reason the body has survived seventy years. |
| Rate | $229/day | The GT 43, on a $750 refundable deposit. The same figure as the AMG GLE 53. |
SL 55 against SL 63: what 108 horsepower buys
Three cars, one badge, and a comparison usually run between the wrong two of them. The SL 55 and the SL 63 differ by a state of tune; the four-door GT 43 differs by an entire body.
The AMG in our garage is the third one, the four-door AMG GT 43; the two SLs are here as the cars people compare it with, with a specification and an argument around each. The rest of the Mercedes range around it is set out in which Mercedes is best to rent.
The SL question is smaller than the search volume behind it suggests. The two cars share a body, a roof mechanism, a cabin, a nine-speed gearbox and the same 4.0-litre twin-turbo V8, with all-wheel drive and four-wheel steering standard on both. What separates them is a state of tune, 469 horsepower against 577, from an engine that 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 ran 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 SL 55 versus SL 63 is the same car, one of them angrier, and the paper is the wrong axis to choose on. The axis that matters is the next section.
The roof is the whole car
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 describe seats with upright backrests 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.
On a folding-roof car the roof lives in the boot, so an SL packs for two people and two carry-ons: a weekend in Santa Barbara. Among our open cars, the Corvette’s hardtop stows in its own well and costs no boot space at all.
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 specification if you want the rest of it. On the coast road at five in the afternoon that trade is a good one.
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 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 coupé 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. It sits low, so steep Hills driveways and the ramp at some Downtown garages want a slow, angled approach; send us the address and we will plan it.
Two things people get wrong, one of them on the phone every week
The SL 63 over the SL 55 buys a figure, not a difference. The 108 horsepower above it is a number you will quote and a thing you will not feel, and both cars carry the same two carry-on bags to the same places. If you are choosing between them on paper, you are choosing on the wrong axis.
A fastback is not a coupé. The GT 43 has four doors and five seats under a roofline that reads as two-door from thirty feet, and the people who ask whether it fits four adults are asking the wrong question — it is the only car of the three that does. What it does not do is put the roof down, and if that is the part you cannot give up, the folding-roof cars we do keep are where to look, and the GT 43 is the answer for every other week.
What actually wears an AMG badge in this garage
Same badge, same rate, and nothing alike. The AMG GT 43 and the AMG GLE 53 both run a three-litre straight-six with EQ Boost, and one is a low four-door fastback while the other is a coupé-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 comparison against the G 550. None of the three puts a roof down, and none of the folding-roof cars we keep is an AMG; say which of those two things matters more and the answer usually writes itself.
What it costs, and how it reaches you
The GT 43 carries a $750 refundable deposit, held rather than spent and back 5–7 business days after the car returns. The Protection plan is priced per day off that deposit band, which puts the GT 43 in the middle of the fleet and well under the exotics; Los Angeles County sales tax at 10.25% goes on the whole booking. Under twenty-five there is a young-driver fee per day, and on the GT 43 it is the lower of the two we charge, because the higher figure starts at a $1,500 deposit. The live calendar and rate are on the GT 43’s page.
Collection from our lot on Robertson Boulevard is free and delivery to the partner hotels in Beverly Hills is complimentary. Airport delivery is $150 both ways standard, where the car waits in the airport parking structure and you take the shuttle out to it, or $300 both ways VIP, where it is waiting at the terminal when you walk out — half that for one direction. On a four-door with a liftback, the parking-structure tier works well. The rest is in the terms.
The short version
Between the two roadsters there is no case for the SL 63 over the SL 55: the 108 horsepower buys a figure you will quote and a difference you will not feel, and both 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 a 1.8-second gap to the SL 63 on Car and Driver’s clock that no road in this county lets you retrieve.
Neither SL is in this garage and the GT 43 is, with its calendar on its own page. If the answer to your week is a roof rather than a badge, say so and we will book the convertible instead — the point is that you get the day you came for.
3 photographs from this guide are free to use under CC BY 4.0 — download them →
Cars in this guide
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Frequently asked questions
What is the difference between the AMG SL 55 and the SL 63?
Nizo Luxury rents AMG cars in Los Angeles — +1 (424) 303-6496 — and the GT 43 is $229 a day. Between the SL 55 and the SL 63 the difference is 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 SL 63 worth it over the SL 55?
Not on any road in Los Angeles County. The two cars share everything except a state of tune, and the extra 108 horsepower is retrievable for perhaps two seconds a day between the 405 and a canyon road with a blind crest every four hundred yards. Both carry the same two carry-on bags to the same places, so the choice between them is the date, not the paper.
SL 63 vs AMG GT 43: which is faster?
The SL 63, by a wide margin on paper. Car and Driver have tested it to 60 mph in 3.0 seconds; the GT 43 makes 362 horsepower from a three-litre straight-six and takes 4.8. 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 is the AMG here: the SL or the GT 43?
The GT 43. Neither SL is in this garage; they are comparison cars. What wears an AMG badge here is the four-door 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 straight-six family, so the choice between those two is about height and luggage rather than performance.
What does the AMG GT 43 hold in people and luggage?
Four adults and their weekend, 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.
How much luggage does an SL take with the roof down?
Two carry-on bags: rated at four to eight cubic feet depending on where the roof is stowed, the boot took exactly two carry-ons in Car and Driver's testing, and the rear seats are useful mainly for putting a bag on. Two people, two carry-ons, a weekend in Santa Barbara.