Check out London-based Adam Schacter's CarGo Urban Delivery Vehicle concept on Coroflot:

Urban traffic congestion is an increasing problem which affects countless delivery companies every day. The unique "CarGo" concept addresses this issue with its variable track, wheelbase and load carrying configurations.

Primarily designed for small, inner city deliveries, the battery powered CarGo's innovative design allows the driver to quickly adapt the vehicle to suit both traffic conditions and load volume/type.

On the other end of the size spectrum is his all-terrain Amphibious Rescue Craft:

The A.R.C. (Amphibious Rescue Craft) is a rugged all terrain vehicle that can be used to deliver vital aid and supplies anywhere required including flooded areas which are inaccessible to most other vehicles. Variable height ground clearance combined with large wheels and all terrain tyres provide excellent off road capabilities, whilst a boat hull and retractable wheels enable the A.R.C to plane at high speeds across water with minimal friction and uncompromised performance.