It's advisable to speak with your accountant first before making that decision.
However, in general terms it is usually not tax efficient to purchase a car through the company due to benefit in kind liabilities. Basically, whatever corporation tax is saved by running the car through the company is almost certainly lost (and extra tax is paid) due to the personal tax liability on the benefit in kind of having a company car.
The better approach would be to purchase the car personally and then charge the company mileage for any business trips you make. Generally, charging mileage at 45p works out to be more tax efficient.