There are so many holes in this report it's difficult to list them all.
- how much auto travel is London to Edinburgh vs. local?
- is fuel consumption the only measure of whether something is enviro friendly?
- are there lighter, lower-consumption trains available, and how would they stack up?
- supposedly the 2004 Passat gets 31 MPG highway. What's the average for those who drive passenger cars between London and Edinburgh?
etc. etc. etc.
If you believe in the global warming theory then yes. Burning hydrocarbons produces CO2. The more fuel you burn, the more CO2.
Prior to the global warming theory, the ideal was to burn fuel cleanly so that all of the exhaust was CO2 and H2O. Pollution was considered to be anything other than CO2 and H2O.