Chassis
As with the 650S, the 675LT uses a single-piece carbon fibre monocell weighing 75 kg, and carbon fibre use in the vehicle is increased in order to further minimise weight and increase rigidity. The 675LT is fitted with new carbon ceramic brake discs to increase braking performance over the 650S. Disc sizes are 394 mm at the front and 380 mm at the rear. Six-piston calipers grip the front discs with four-piston caliper used for the rears. Braking performance is also aided by the air brake ability of the new rear wing.
The 675LT makes use of a new 10-spoke wheel design, each weighing 800 g less than the alloy wheels on the McLaren P1, supplied in a 19-inch front and 20-inch rear fitment.
The new wheels are fitted with Pirelli P-Zero Trofeo R track-focused, street-legal tyres which increase grip by up to 6% over the P-Zero Corsa sold with the 650S.
Body and cabin
The length of the 675LT is 1.3 in more than the 650S. The 675LT utilises a new rear wing/air brake assembly 50% larger than that used in the 650S, along with a new carbon fibre diffuser and an 80% larger front splitter with sizeable endplates that together increase total downforce by 40%.
New carbon fibre pieces include both the front and rear bumpers as well as front undertray, rear fenders, side intakes and decklid that contribute to the significant weight savings over the 650S.[23] Alcantara is used throughout the interior where carpeting is removed and removal of the air conditioning unit and new carbon fibre race seats together save 26.5 kg although an adjustable passenger seat and air-conditioning are included as no-cost options. Other differences from the 650S' interior include the integration of climate controls into the centre console mounted touch screen. 1 millimetre thinner window glass further reduces weight by 3 kg. New 10-spoke forged aluminium wheels with titanium wheel nuts reduce weight by 1.8 lb. This extreme focus in weight saving results in a dry weight of 1230 kg, 100 kg less than the 650S.[23][24]
Drivetrain
The car is powered by a variation of the M838T 3799 cc twin-turbocharged V8 engine rated at 675 PS at 7,100 rpm and 700 Nm at 5,500 rpm. This is achieved through the addition of new lightweight connecting rods, a bespoke camshaft, an electronic recirculation valve and a lightweight titanium exhaust featuring dual circular outlets. Also used in the engine are revised turbocharger compressor wheels and an optimised fuel pump.[25]
The 675LT uses the 7-speed automatic dual-clutch gearbox used in the 650S, with improved software reducing the shift time.[25]
The 675LT can accelerate from 0–100 km/h in 2.9 seconds, 0.1 seconds faster than the 650S. 0–200 km/h in 7.9 seconds, 0–300 km/h in 25.9 seconds, 0–200 mi/h in 31.2 seconds, and do the 1/4 mi sprint in 10.3 seconds at 141.1 mi/h,[26] continuing on to a claimed top speed of 330 km/h.[27]
Nomenclature
The 675 in the 675LT model name refers to the power output of 675 PS, following the naming scheme started by the 650S. The LT in the model name is a reference to the "Long Tail" 1997 McLaren F1 GT which was the final incarnation of the F1 road car built to comply with FIA homologation regulations for the 1997 F1 GTR. The F1 GT featured extended front and rear overhangs that produced similar downforce to the previous homologation special, the F1 LM, without the use of a drag-inducing fixed rear wing.
675LT Spider (2016–2017)
A convertible variant of the 675LT was revealed online in December 2015. It shares the same 675 PS, 3.8-litre twin-turbocharged V8 engine as the coupé, but has a folding hardtop roof as seen on the 650S Spider taking 16 seconds for operation. The 675LT Spider can accelerate from 0–100 km/h in 2.9 seconds and 0–200 km/h in 8.1 seconds. The top speed is reduced slightly, to 327 kph.[28] McLaren only built 500 675LT Spider (without counting special editions such as the Carbon Series).[29]
675LT Spider Carbon Series
In June 2016, McLaren publicly released the 675LT Spider Carbon Series. The cars are based on the 675LT Spider and have the same engine and performance. An extra 40 per cent of the body panels are carbon fiber such as the retractable roof and tonneau, A-pillars, bonnet and rear deck, side blades, complete front and rear wings, and even fuel filler flap. Only 25 Carbon Series have been built bringing the total number of 675LTs Spider to 525.[30]
MSO HS (2016–2017)
The McLaren MSO HS is a limited version of the outgoing 650S model and is based on the 675LT variant, inspired by the McLaren P1 GTR. It was introduced online in late 2015 and publicly in August 2016.[31] The car is lighter and more powerful than the 675LT, the upgraded engine now rated at 688 PS and 516 lbft of torque at 7,000 rpm. The car is approximately 19 kg lighter than the 675LT thanks to the use of Alcantara interior upholstery and carbon fibre racing seats with racing harnesses similar to those found in the P1 GTR, although, a Nappa leather interior upholstery is optional. Exterior changes include a new bumper with front splitters, roof mounted air scoop, full length side skirts and an adjustable fixed rear wing, inspired by the P1 GTR. The wing can be adjusted electronically via the settings programmed in the car's computer. Overall exterior modifications of the car help generate 220 kg of downforce at 150 mi/h. Only 25 were made with each car fully customisable by the customer, bringing the total number of 675LTs to 525. Performance figures of the car remain unknown but the car is likely to have improvements in acceleration, handling and top speed.[32]
MSO R
In October 2017, McLaren announced the one-offs MSO R Coupe and MSO R Spider both ordered by the same customer. The cars use the same engine as the MSO HS. One way to differentiate the MSO HS from the MSO R is with the rear wing which has 2 levels on the MSO R. Both cars are silver but the coupe has a matte finish. The cars have been seen wearing German license plates with the coupe's reading "M RR 688" and the spider's reading "M SR 688".[33]