auto<- read.table("../data/auto.dat", header=TRUE)
auto$city.consumption =1/auto$city.distance
n <- nrow(auto)
pairs(auto[,
    c("city.distance", "engine.size","n.cylinders","curb.weight")],     
    labels=c("City\ndistance", "Engine\nsize","Number of\ncylinders",
           "Curb\nweight"),
    cex=10/sqrt(n)  )

fit = lm(city.consumption~engine.size,data=auto)
plot(auto$engine.size,auto$city.consumption)
abline(fit$coef,col=2)