For the Van os Medical Excel G Logic wheelchair, you could contact the manufacturer/sales people. I am sure they can give you the dimensions of the folded wheelchair, to help in your car search.
VanosMedical
Excel House
Ashbrooke Park
Sherburn in Elmet
North Yorkshire, England, LS25 6 PJ
Phone: +44 (0) 1977 681 400
Sales@vanosmedical.com
For the Karma Ergo Lite 2, try speaking with:
Karma Mobility
Unit 6 Target Park
Redditch
Worcestershire, UK
B98 8YN
Tel: 0845 630 3436
Fax: 0845 630 3736
info@karmamobility.co.uk
Dave