Maybe not a long term alternative but taxing drivers behaviour via extreme penalties rather than the type of fuel or vehicle they use would not only raise revenue but may also encourage people to drive in a safer and more fuel-efficient manner?

For example, overtaking a cyclist regardless of the fact that you are already approaching a stop junction should result in a fine of at least £10,000.

Tailgating in a dangerous and aggressive manner, £50,000.

From everyday observation, this would raise a few billion in no time at all and price some very stupid and aggressive people off the roads entirely.