I am of the opinion that the only true competition on European soil for the S550 is going to come from the Germans. The Camaro is egregiously over priced, Alfa hasn't made a decent sports car in years (4C is priced out of range pipe down ), Even the hot hatches have become relatively dowdy as of late. The list is shimmed even slimmer when you consider open top motoring, unless you're in the market for something as tedious as say the Vauxhall Cascada your strongest cabriolet options seem to be the 4 series, the A5, the SLK and eventually the EcoBoost Mustang.
It is tricky to gauge accurately considering S550 has neither a price or official specs of any kind. Regardless, lets see if we can make some inferences.
Ford S550 EcoBoost Mustang Convertible- Pricing N/A
What we do know about the Ecoboost Mustang is that it will utilize a 2.3L Twin Scroll Turbo I4 projected to make north of 300 horsepower and 407+ Nm of twisting. CO2 figures are also missing in action as of now, but if you consider the Focus ST with the 2.0L EcoBoost engine that emits 169 g/km the Mustang should not be far off. However the 2.3L in the S550 does utilize new technology missing from the 2.0L. The low inertia twin scroll turbo is supposed to lower emissions and boost efficiency because the boost shows up lower in the band meaning you don't need to work the throttle as much to find power. Plus seperated exhaust posts allow the valves to stay open longer which minimizes consumption. Ford is saying the new port design should improve fuel economy by 1 percent. Not much, but would you rather it worse by 1 percent?
Mercedes SLK- £34,345 (including VAT, no OTR)
SLK may not be a direct compare with the Mustang considering it is more of a roadster, but if you're writing the cheque I imagine you dictate just who is competing for your funds. The bottom of the barrel SLK will run start you off with diesel motivation, However it is only a short hop to the 1.7L I4 petrol. That engine makes 184 hp and 250 Nm of twist with combined CO2 outputs of 158.0 g/km. A far cry from the Ecoboosts proposed power figures and wrapped in a 1435 kg package, which is still lighter than the S197 Cabriolet with a V6. SLK may be too punchless to offer a serious brand of enjoyment, but it is a Mercedes however so I suppose there is that...
BMW 428i SE Convertible- £37,015 (OTR Price)
At 37K the 428i Cabrio is the priciest of the bunch, however I do view the 428 as the single biggest rival due to its refinement and focus on dynamics that really is the BMW brand. Plus people love to been seen in their BMW's which always has funny psychological effects, but enough with the babbling. The 428i SE will make 245 hp and 350 Nm from its 2.0L TwinPower Turbo 4 cylinder. With the 6 speed manual the BMW shows CO₂ emissions of 159-163 g/km. However the BMW does have one major fault, its a porker the heaviest at the bunch actually, tipping the scales at a buffet busting 1755 kg. For reference that is 110 kg's heavier than the outgoing mustang with a V6.
Audi A5 Cabriolet SE 1.8 TFSI- £31,965 (ROTR)
The Audi is the cheapest of the Teutonic trio and for good reason as well, the A5 is the only front wheel drive choice of the bunch. It is available with Quattro, but of course that will cost you. In SE trim, the 1.8L Turbo I4 will make 170 hp and 320 Nm of torque. While it does make the lowest power output the A5 does make an impressive amount of torque. With the 6 speed Manual the A5 makes CO₂ emissions of 143 g/km. The A5 Cabriolet is also quite the heavy car, tipping the scales at an ugly 1620 kg, just 26 kg lighter than the S197 Mustang Convertible with the V6 engine.
And so, do you think the Mustang will be able to make a dent in any of the incumbents?