> speed.mod1 <- lm(topspeed ~ cbank + clength + cbl + cbank2 + clength2)
> summary(speed.mod1)

Call:
lm(formula = topspeed ~ cbank + clength + cbl + cbank2 + clength2)

Residuals:
     Min       1Q   Median       3Q      Max 
-10.3401  -2.1590  -0.3242   3.4285   8.2079 

Coefficients:
             Estimate Std. Error t value Pr(>|t|)    
(Intercept) 182.87290    1.70630 107.175  < 2e-16 ***
cbank         1.47430    0.15158   9.726 7.19e-08 ***
clength      43.85323    2.05382  21.352 1.22e-12 ***
cbl           0.04550    0.17616   0.258    0.800    
cbank2       -0.01405    0.02155  -0.652    0.524    
clength2    -30.76135    4.03282  -7.628 1.54e-06 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 5.524 on 15 degrees of freedom
Multiple R-squared: 0.9755,     Adjusted R-squared: 0.9674 
F-statistic: 119.6 on 5 and 15 DF,  p-value: 1.549e-11 

> aov(speed.mod1)
Call:
   aov(formula = speed.mod1)

Terms:
                    cbank   clength       cbl    cbank2  clength2 Residuals
Sum of Squares   2640.077 11898.463     0.001  1933.301  1775.705   457.793
Deg. of Freedom         1         1         1         1         1        15

Residual standard error: 5.52445 
Estimated effects may be unbalanced
> plot(speed.mod1)
> 
> speed.mod2 <- lm(topspeed ~ cbank + clength + clength2)
> summary(speed.mod2)

Call:
lm(formula = topspeed ~ cbank + clength + clength2)

Residuals:
     Min       1Q   Median       3Q      Max 
-10.1114  -2.3861  -0.1848   3.6069   8.4004 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept) 182.6518     1.5972  114.36  < 2e-16 ***
cbank         1.4639     0.1437   10.19 1.18e-08 ***
clength      44.1705     1.9176   23.03 2.94e-14 ***
clength2    -32.5218     2.8254  -11.51 1.90e-09 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 5.279 on 17 degrees of freedom
Multiple R-squared: 0.9747,     Adjusted R-squared: 0.9702 
F-statistic:   218 on 3 and 17 DF,  p-value: 9.156e-14 

> aov(speed.mod2)
Call:
   aov(formula = speed.mod2)

Terms:
                    cbank   clength  clength2 Residuals
Sum of Squares   2640.077 11898.463  3692.969   473.832
Deg. of Freedom         1         1         1        17

Residual standard error: 5.279436 
Estimated effects may be unbalanced
> plot(speed.mod2)
> plot(cbank,speed.mod2$residual)
> plot(clength,speed.mod2$residual)
> 
> 
> anova(speed.mod1,speed.mod2)
Analysis of Variance Table

Model 1: topspeed ~ cbank + clength + cbl + cbank2 + clength2
Model 2: topspeed ~ cbank + clength + clength2
  Res.Df    RSS Df Sum of Sq      F Pr(>F)
1     15 457.79                           
2     17 473.83 -2   -16.038 0.2628 0.7724
> 
>