Two things,the higher the number of the diff ratio the more acceleration ie 4:1/5:1, the lower more top end less quick acceleration and in any case the car weighs many times less than the old Granny but then factor in the aerodynamics of of a 600kg brick and you will have you top speed.
you will get to 60mph quicker than most exoctics costing £100,000 and more for a lot less money and much more fun.
Edit: as TT says getting it on the ground is the problem with such a light car.