We read a lot of comments about EVs online and how they can never be true sports cars. Some people say they will be too heavy, some people say they have no manual gear box and some people say they won't have the sound of a combustion engine. Well these are our thoughts on why we think you can build a great sports car as an EV.
Having owned a lot of interesting cars over the years, including a Lotus Elise, Subaru Impreza Turbo, MX-5 (NA and ND) and a Fisher Fury R1, these are the things that we consider important to driver involvement:
Lower mass makes for much better driver involvement. A lighter car simply changes direction better and provides a better connection between the driver, the car and the road. Rob's Lotus Elise S1 was simply brilliant at connecting with the driver even at slow speeds but, stepping into his 450kg Fisher Fury R1 made the Elise feel like a bus. This is a car that your wear rather than drive. It is like riding a motorbike off road and then doing the same route on a mountain bike. You simply feel much more, you are better connected and you can respond more quickly to the amplified inputs to your senses. The feedback to the driver is much less filtered too. It does require much greater concentration though and this Fisher Fury R1 is too extreme for our OSSEV® project requirements.
Good weight distribution is important for confidence and feel on twisty roads but, a lower centre of gravity also makes a huge difference. Rob's Fisher Fury R1 sat so low on the road that you sat below the wheel centres. This meant being pushed down into the seat when cornering hard as opposed to sliding on the seat. It also had a near perfect 50:50 front/rear weight distribution.
Our MX-5e will be lighter than the Eunos Roadster that we started with. We have stripped all of the ICE related things that made it heavy to start with. We are saving a lot of weight by removing things that are no longer needed in an EV such as heat shield, excessive cooling system, sound deadening, exhaust system, fuel tank, power steering, air conditioning, etc. We have also removed the soft-top, fitted a much lighter wiring loom, lighter seats, etc. Our target weight is 970kg.
The primary interface between the driver and a car is the seats. It's the part that provides the most feedback and interfaces with most of your body. In an ideal sports car this would be a custom shaped hard shell seat like the Tillet seats used in Rob's Fisher Fury R1 but, these are too extreme for our intended usage. They are also incredibly comfortable if they are a perfect fit for the driver. Good support is the key. Having taken cars on track with unsupportive seats, we know how much strain they can put on your chest, hips and shoulders.
We are still searching for the best seats to go in our MX-5e. We need something supportive, adjustable and ideally capable of working with a 6-point harness.
The secondary interface between the driver and a car is the steering wheel. When on the move it provides pure feedback on the road surface and the cars connection with it. In many modern cars this connection is broken to make driving a more relaxing experience and the steering rack ratio is chosen to ensure the car is not too responsive to steering wheel input and provides a nice 'weight' to the steering.
In Rob's Fisher Fury R1 there is a very fast steering rack, with no power assistance. The steering is perfectly weighted but, the car demanded 100% concentration or you would end up in the hedge. Minimal steering input was required and it was very easy to catch any over-steer.
In the MX-5e we have properly depowered the steering and are keeping the standard ratio with a simple 260mm diameter Momo steering wheel to provide a nice balance between steering weight, feel and responsiveness. We don't want something too extreme as the MX-5e is going to be a car for anyone to enjoy. The size, feel and material of a steering wheel has a big part to play too. We have not spoilt the steering by using huge wheels and tyres for cosmetic reasons.
Brakes have to inspire confidence and provide a great feel, so you can be sure your car is going to stop consistently in a set distance and from any speed. You obviously have to factor road conditions into this and a great sportscar will be providing you detailed information on this too.
Rob's 450kg Fisher Fury R1 had astounding braking once the Yokohama A048R tyres were up to temperature. He has never driven another car that can stop so quickly. A large part of this was down to the 450kg mass and the super sticky tyres but, it also had perfect brake balance front and rear, set with a brake bias adjuster. The brakes were also unassisted, to provide a superb feel and the calipers and brake cylinders were chosen specifically to facilitate this.
With the MX-5e we are doing all we can to improve the braking system. There was no ABS in the Eunos Roadster and there will be none in the MX-5e. Like the OSSEV®, it is designed to be driven by anyone, so we are not making it too extreme. Both are designed to be light-weight though. We have an iBooster to provide electric brake assistance and to deliver custom regenerative braking based on driver profile and driving profile. This means the regenerative braking can be disabled in the sportier driving profiles. The brake bias front and rear will be set optimally. We have kept the standard Eunos Roadster brake calipers and discs as these are easily up to the job of fast road driving (our primary use case). We have fitted EBC Greenstuff pads to ensure good stopping power when the brakes are both cold or hot and we have fitted stainless-steel braided brake hoses to improve the brake feel.
We have lowered the MX-5e about 25mm and have fitted MeisterR coil overs to improve the handling and reduce the body roll. We have also completely refurbished the suspension with new polybushes, ball joints and alignment bolts. Professional geometry alignment will also be done.
With the MX-5e we have spent a lot of time getting the instruments and controls right, to provide an intuitive and great user experience, with manual buttons and switches to hand. None of the main functions require a touch screen to operate. This includes instant and linear throttle response, with a throttle pedal that is well positioned and enables fine control.
We are implementing personalised driving profile for each driver profile. These allow the MX-5e character to be changed to meet your current needs. Sometimes you need a relaxing driving experience and sometimes you want something sporty.
We hear a lot of people say that it can't be a proper sports car if it doesn't have a manual gear lever/shift. Our view is that a gearbox is only there to overcome the limitations of the internal combustion engine, especially the narrow power band and lack of torque at lower revs.
Whilst we agree there is a lot of fun to be had changing gears, a manual gear lever is not the best way to change gear. Even the best gear shift is clunky and takes a long time to achieve its purpose. This is why race cars use paddle shift mechanisms, as Rob did in his Fisher Fury R1. This is the way to change gear! 😎 This YouTube video shows a direct cable connection to the 6-speed sequential gear box, so you can feel what the gearbox is doing, through the paddle shift. There are no electronics involved and it requires the clutch to be used too.
A well set up EV is always in the right gear and always provides instant torque and throttle response. Whilst some people miss the gear changes, you soon realise that this is a tiny part of what makes a sports car. It allows you to focus and concentrate on all the other elements of fun driving, without the distraction of having to take your hands of the steering wheel and without the delays associated with changing gear.
With the MX-5e we have designed the transmission to be a perfect balance between acceleration and top speed. The instant throttle response and torque is perfect for UK twisty B-roads. Maximum torque is instantly available on the exiting corners and fine throttle control through corners is possible, without having to worry about changing gear. Similarly, EVs are great at handling rapid changes in elevation whilst allowing the driver to focus on the road ahead.
We love petrol engines and Rob lover the 12,000rpm red-line on his Fisher Fury R1 but, once you get used to the a good EV, you realise that the noise is a distraction from to the real driver involvement and you don't miss the noise. Your mind refocuses on all the other senses and your connection to the car and road that you feel through your seat and the steering wheel becomes the real essence of the driver involvement.
We have kept with 15" rims on the MX-5e and reduced the unsprung weight by using lighter wheels and sports tyres. We are also using 7" rims to ensure the tyres are not excessively wide and negatively impact the handling and feedback.
