You didn't used to get taxed for having a van but they brought that in a while back. The only way round it say for example, you drive to your employers in your own car or get bus whatever and only use the van from the employer to the place of work/site and back to employers, then your own transport. If you drive from home to site then its classed as personal mileage.
When I had a company car I was always out at customers and rarely went into office. When it came to filling in mileage forms, because I lived 7 miles away from work I had to deduct 14 per day off my total travel as that was my personal mileage to and from my place of work.
