How friction is reduced in fast moving vehicle?

Suppose you want to minimise the waiting time of vehicles at a traffic junction of four roads. Which of these factors are important and which are not? (i) Price of petrol. (ii) The rate at which the vehicles arrive in the four different roads. (iii) The proportion of slow-moving vehicles like cycles and rickshaws and fast moving vehicles like cars and motorcycles.

Friction produces heat. How ?

How can force of friction be reduced ?

How do you account for function of mudguards in vehicles?

How do fish move ?