I’ve always wanted to build my own car: the idea of driving something unique as well as having total control of the specification appeals to me. However, achieving this dream would require vast amount of space, time, money and tools, all far beyond my current capabilities.
Therefore, when I saw an advert for a decrepit G-Wiz on Gumtree, I couldn’t help but think that heavily modifying a car is just as good as building one (or at least a reasonable stepping stone).
The small form factor means that it will fit in the garage. It’s also exceptionally light so there is no need for specialist ramps or lifts (400kg sans batteries), and it’s already registered for the road so saves a ton of paperwork and red tape with the DVLA.
According to howmanyleft.co.uk, as of Q1 2025, there were only 356 of these vehicles remaining, with only 45% still being on the road, so this almost ticks the box for uniqueness.
This red example had fewer than 10,000 miles on the clock and had the huge selling point of being the only one available in the UK at the time. So I bought it sight-unseen and got it transported with anyvan.co.uk.
The Plan
The plan is simple: get the car back on the road.
The exact route this plan will take is very much TBC; at a minimum the vehicle requires a new battery pack and associated battery management system, but a motor upgrade isn’t beyond the scope of this project.
The original system worked with eight 6V lead acid batteries to give a nominal system voltage of 48V while weighing over 250kg! The power from these batteries would be fed through a Curtis motor controller rated for 350A to a three phase “squirrel cage induction motor” rated for 6kW (or 13kW when on boost). The theoretical max power of the motor controller is 17.6kW, so I can only assume the squirrel has escaped from it’s cage.
So the general plan is to address the two main points which contributed to the G-Wiz winning the prestigious title of Top Gear’s Worst Car of The Year 2007 were:
- The lead acid batteries are heavy and have relatively poor power density when compared to modern lithium technology. For example; the energy density (by volume) of a lead acid cell is about 0.25MJ/L, whereas a LiFePo cell is 1.43MJ/L – over five times greater!
- AC synchronous motors have poor starting torque due to the lack of permanent magnet and also struggle with varying speeds and loads. Changing the motor to a BLDC or PMSM motor would greatly improve this, but also add complexity and cost.
Thankfully there are a couple of well documented tutorials on converting these cars to the more efficient lithium-ion battery chemistry, but there seems to be no instances of the motors being modified/upgraded (aside from the remote controlled version produced by Lynch Motors for an episode on Top Gear).
While both of these items individually are no small task, I fear the most difficult part of this project will be sourcing a new off-side wing mirror.
What next?
This is a long term project, so the first step is to wait until the V5C comes from the DVLA: how this vehicle is classified will likely effect the available modifications. After that will be the agonising process of researching, designing, specifying and most importantly: saving the money!
The speed of this project will be dictated by funds (or lack of), but I would like to get this on the road by December 2026 as this would be twenty years after the vehicle was originally registered.
In the meantime, here are a couple of photos.
