and a regular car have effective frontal areas of about 0.8 m^{2} and 0.5 m^{2} re-

spectively, a full commuter train from Cambridge to London has a frontal

area per passenger of 0.02 m^{2}.

But whoops, now we’ve broached an ugly topic – the prospect of sharing

a vehicle with “all those horrible people.” Well, squish aboard, and

let’s ask: How much could consumption be reduced by a switch from

personal gas-guzzlers to excellent integrated public transport?

At its best, shared public transport is far more energy-efficient than indi-

vidual car-driving. A diesel-powered **coach**, carrying 49 passengers and

doing 10 miles per gallon at 65 miles per hour, uses 6 kWh per 100 p-km –

13 times better than the single-person car. Vancouver’s **trolleybuses** con-

sume 270 kWh per^{E} vehicle-km, and have an average speed of 15 km/h. If

the trolleybus has 40 passengers on board, then its passenger transport

cost is 7 kWh per 100 p-km. The Vancouver **SeaBus** has a transport cost

of 83 kWh per vehicle-km at a speed of 13.5 km/h. It can seat 400 people,

so its passenger transport cost when full is 21 kWh per 100 p-km. London

**underground trains**, at peak times, use 4.4 kWh per 100 p-km – 18 times

better than individual cars. Even **high-speed trains**, which violate two of

our energy-saving principles by going twice as fast as the car and weighing

a lot, are much more energy efficient: if the electric high-speed train