# McMurtry Spéirling

The McMurtry Spéirling is an electric single-seat prototype sports car which was first presented at the Goodwood Festival of Speed in 2021. The car is developed by McMurtry Automotive, a British registered startup founded on 2 June 2016 by Sir David McMurtry (co-founder and executive chairman of Renishaw plc). "Spéirling" is Irish for "thunderstorm".

## History

According to McMurtry, the motivation behind the car was to challenge the industry trend of increasingly heavier vehicles and, by using first principles design, create a lightweight electric driver's car. The prototype car is the first step to demonstrate what customers will experience on road and track. It is not currently in a racing series but is built to satisfy relevant motorsport safety requirements, with crash structures and a carbon-fibre monocoque chassis with integral rollover protection. Its unique performance differentiator is the fan-powered downforce system, producing 2,000 kg (4,400 lb) of downforce at a standstill.
The car, developed in secrecy over three years, was first presented at the Goodwood Festival of Speed on 8 July 2021, and driven by Derek Bell.
On 26 June 2022, the Spéirling achieved a new Goodwood Festival of Speed hill climb record, completing the 1.87-kilometre (1.16 mi) course in 39.08 seconds with McMurtry test driver Max Chilton behind the wheel.
In December 2022, it set the following times verified by independent GPS timing without rollout by Mat Watson from carwow on Silverstone:
* 0-97 km/h (60 mph) in 1.55 seconds
* 0-161 km/h (100 mph) in 2.63 seconds
* 0-233 km/h (145 mph) in 4.98 seconds
* 400 m (approx. 1⁄4 mile) in 7.97 seconds
When considering the 1⁄4 mile time, the car had a 249 km/h (155 mph) top speed for roughly the last 3 seconds of the run. The car also ran on bespoke drag slicks and was not a production car model.

## Specifications

Below are the specifications for the Spéirling PURE:
* Peak power output: 745 kW (1,000 hp)
* Top speed: 298 km/h (185 mph)
* 0-97 km/h (60 mph) in 1.55 seconds
* 400 m (approx. 1⁄4 mile) in 7.97 seconds
* Weight: 900 kg (1,980 lb)
* Battery capacity: 100 kWh
* Rear wheel drive
Estimated driving time on a race track at a GT4 pace is about 25 minutes.
The car has rear-wheel drive using two electric motors placed inside a specially designed "e-axle", and uses carbon brakes. The monocoque has room for a driver 150 to 200 cm (4.9 to 6.6 ft) tall. The battery is integrated into a separate safety cell inside the monocoque.

### Active downforce

A special design aspect of the car is its active downforce system without the use of large splitters or wings, by means of twin fans which provide an extra 2,000 kg (4,400 lb) of downforce from a standstill. This allows the car to corner at a G-force of more than 3g. When the fans are at full speed, they emit about 120 dB of noise.
The use of fans powered by separate motors to provide downforce was first conceived of by Jim Hall for the Chaparral 2J, a Can-Am car he designed, constructed and raced in 1970. However, the 2J was banned at the end of the 1970 Can-Am series. A downforce fan system was also used in the Brabham BT46B Formula One car, which was designed by Gordon Murray. The BT46B raced at the beginning of the 1978 season to great effect before a rule change was made under pressure from other race teams, resulting in a ban on movable aerodynamic surfaces.

### Tyres

The tyre width is 210 mm (8 in) on the front and 240 mm (9 in) on the rear, both on 19 in (483 mm) rims. This is modest for a sports car and is comparable with regular road cars which tend to have tyre widths from 195 to 205 mm (7.7 to 8.1 in).