Edmiston came 152nd in the Sunday Times rich list which was published on April 27.
The automotive industry had a strong representation within the list.
Sir Arnold Clark came in at second wealthiest in the automotive industry with £365 million, 244th overall.
Top 10 wealthiest in the automotive industry
1. Bob Edmiston IM Group £520m (152)
2. Sir Arnold Clark Arnold Clark Automobiles £365m (244)
3. Jack Tordoff JCT600 boss £210m (380)
4. Sir Peter Vardy ex-Reg Vardy owner £150m (525)
5. Keith Bradshaw owner of Listers Group £140m (564)
6. Sir Tom Farmer Kwik-Fit founder £130m (597)
7.Tony Bramall Bramall & Jones boss £120m (644)
7. Abe Jaffe Currie Motors boss £120m (644)
8. David Blackburn Colt Car Company boss and owner of Spitalgate Dealer Services £115m (701)
9. Sukpal Singh Ahluwadia Euro Car parts boss £100m (784)
10. Paul Dunkley Camden Motor Group chief executive £90m (879)