The business, which supplies vehicles to clients across southern England, has added covered valet and vehicle preparation areas to its base at Gawcott.
It has also improved facilities to include the provision tracking devices and sign writing.
Managing director Peter Abdale said: “Expanding our Buckingham site has allowed us to offer increasingly bespoke service to our customers in the South and South East so it is great news for our growing company.”
The firm employs 17 staff and has more than 40 drivers operating from the site, one of four branches in the UK.
The expansion follows a period of successful growth for the company, with turnover across the UK reaching £16.1 million in 2016 and an expected increase to £20 million for 2017.
Transflex was recently ranked 13th in the Sunday Times Fast Track 100 League.
