He believes the issue is not just lack of passing power, etc., but the low-HP engine over-works and will have problems earlier. Any comments, please.
There are a couple of things wrong with your brother's statement:
#1. I'm tired of people saying the 5 is underpowered! I can understand automotive journalists who just returned a 270HP Toyota Camry and then got the 5, but in real world terms, it is a very peppy car. Perhaps my judgement is clouded? My Chain of cars has been '77 Volvo 4-cyl (100hp, 3000 lbs) -> '94 Mercury Sable V6 (140Hp, 3400-ish lbs) -> '01 Toyota Echo 4-cyl (108HP, 2100 lbs). If anything, the Volvo was underpowered, but could still cruise with ease (up to about 70mph, but gearing limited fasted speeds). I have driven the 5 with 4 adults on a 2-lane highway and it passed just fine. It didn't slam you back in the seat with acceleration, but no can I've driven ever has. The only thing I can say about the 5 auto is that it's a bit lazy to down shift so it tends to drop to 3rd and build power, which could contribute to the perception of lack of power.
#2. Smaller engines are not over-strained and aren't going to wear out any faster. Generally the thing that kills an engine is heat. Lugging an engine will build heat much quicker than running at moderate to higher RPM. Granted, running any Engine at red line and especially beyond will shorten life. My old Volvo 4-cyl only had a 4-speed, so at 70 MPH, it was turning over 4000 RPM. A highway passing maneuver could see near 6000 rpm (the engine had a red line of 6200 RPM). there are many performance cars out now with an 8000+ RPM redline and motorcycles that have a 12000+ RPM redline)
My theory is that a lot of people either are listening to the journalists, are full of min-information, or are using anecdotes from many years past. The traditional American pushrod Engine tended to have a redline of 5000 or less RPM, and even running at 4000 RPM could cause pushrod flex and damage. Technology has advanced and overhead cam engines are perfectly happy running at high rpms with proper care.
Also, I suppose the practical side of me says that it makes more sense to have a small engine that you need 100% of the available of power in some situations, rather than a larger engine where you never really 'need' to use 100% of the available HP. My Toyota Echo makes due with a 1.5 L 4-banger, running in the 3000-4000 RPM range all day long and ought to be good for years to come. It may be a bit buzzy and take some 'planning' (as the journalists say) when passing on the highway, but it also returns over 30 MPG in daily city driving.
