This is taken from Sammo on the .net (Netmag) Forum from a year or so ago. I agree with it and I can’t wait until I get to the Monster Truck stage:

I reckon you should have to earn your way up through the transport strata. You know:

• socks on polished floors
• skateboard
• Rayleigh chopper
• mobilette
• scooter
• milk float
• reliant robin
• <100 hp car
• ice cream van
• >100 hp car
• tractor
• family saloon
• monster truck
• harrier
• space shuttle