Introduction

I wanted to take a look at the horsepower of a car model over time. The Chevrolet Corvette fit this perfectly as its been in production since 1953, except one year in 1983 due to quality control issues, and has always been a sports car.

Data

Horsepower was collected for all engine options per year of production. The generation needs to be calculated though where:

• C1 1953-1962
• C2 1963-1967
• C3 1968-1982
• C4 1984-1996
• C5 1997-2004
• C6 2005-2013
• C7 2014-present

# Read in data
data <- read.csv("C:/code/corvetteHP/2015-08-13-corHP.csv")
# Calculate generations
data$Gen <- ""
data$Gen[data$Year >= 1953 & data$Year <= 1962] <- "C1"
data$Gen[data$Year >= 1963 & data$Year <= 1967] <- "C2"
data$Gen[data$Year >= 1968 & data$Year <= 1982] <- "C3"
data$Gen[data$Year >= 1984 & data$Year <= 1996] <- "C4"
data$Gen[data$Year >= 1997 & data$Year <= 2004] <- "C5"
data$Gen[data$Year >= 2005 & data$Year <= 2013] <- "C6"
data$Gen[data$Year >= 2014] <- "C7"

Graph

Graphing the data using ggplot:

library(ggplot2)

ggplot(data, aes(x=Year, y=HP, colour=Gen)) + geom_point() + 
  ylab("Horsepower") + ggtitle("Chevrolet Corvette Horsepower per Year") +
  scale_x_continuous(breaks=c(1953, seq(1955,2016,by=5))) +
  theme(axis.text.x=element_text(angle=45, hjust=1)) +
  scale_colour_brewer(palette="Paired") 

The big trend is in the 70s, with a drastic cut in engine horsepower. This was a bunch of different variables coming into play at the same time. First off SEA net power was used which results in a lower advertised but more realistic value of the horsepower ratings of the vehicles. As well as the move away from lead fuel, resulted in lower compression ratios to run regular instead of premium gasoline, further reducing the overall horsepower of the engine. As well as the energy crisis brought fuel economy to the forefront shifting peoples views away from big gas guzzling motors.

Since the late 80s, the Corvette has been on the upward swing in terms of horsepower, greatly helped by new technologies that are always coming up. Lighter materials and better engine design keeps pushing the limits of this American sports car.