A casual observer might look at the six roadsters in this article and assume they're similar. They all have sleek lines, taut suspensions, and their tops go down for sunny-day play. But each is a machine with its own distinct personality, perfectly honed for a particular type of buyer. From the Corvette's all-American tire-burning torque to the Honda S2000's super-high-revving motorcycle-like power delivery, and from the Boxster's basic Germanic sporting approach to the Audi TT's flamboyant deco/mechanical design, there are as many different flavors as nameplates. We've also included "future" roadsters from Toyota and Mazda. That's the fun part-sampling them all to decide which is best for you.
Power Plays
Where gasoline prices aren't as low as they are in the U.S., the name of the game is small-displacement engines that yield a high power-to-weight ratio. Not only does a favorable ratio translate to accelerative quickness and fewer DM, , or spent at the petrol station, but light weight allows a driver to interpret, predict, and react to what the car's telling him so he can push it to its most enjoyable extreme.
In our group, Toyota's roadster is the least aggressive at exploiting the power-to-weight ratio. The lightest car in the test at 2210 pounds, the MR2 Spyder also has the least powerful 1.8-liter engine at 140 horsepower-moving 16 pounds of car around with each horsepower produced. Not exactly the stuff of legend. On the other hand, Mazda's 1.8-liter Mono-Posto squeezes 50 more horses from essentially the same size engine with a turbocharger and free-flow plumbing from intake to exhaust. Pumping out 103 horsepower/liter, its estimated 2500-pound curb weight produces a 13.1-horsepower/weight ratio. Audi adds some compression (but also an extra valve) to its four-cylinder, 1.8-liter engine with a turbocharger and its new five-valve-per-cylinder head. This liberates 225 horses (or a whopping 126 horsepower/liter) and drives the heaviest car in the test at all four wheels with a 14.9:1 ratio. The BMW M Roadster relies on no such force-feeding tactics with its notoriously smooth inline-six. The 3.2-liter engine is as happy in the low end of its tachometer as it is to rev to its redline. This power and a lightweight package conspire to deliver an exuberant 12.8-pound/horsepower ratio. The most finicky engine of the group is in Honda's S2000. To extract just over 120 horsepower/liter in a naturally aspirated engine, you need to make it spin really, really fast-and it does, to 9000 rpm-an astronomical number for a production car. Its split-personality 2.0-liter I-4 allows the little road-rocket to boast quick reflexes and a nimble 11.7-pounds/horsepower ratio. Porsche's highly tuned, midship-mounted 3.2-liter horizontally opposed six nudges the fun needle yet further and delivers a free-revving and responsive powerband that needs to hustle only 11.4 pounds of car per pony-and it sounds so sweet doing so.
However, if it's neck-snapping power you crave, then the Corvette is what you need. Though specific output per liter is low at just over 60 horsepower/liter, the Corvette's American V-8 makes up for it with 5.7 liters of displacement. One can almost hear each individual cylinder surrender its spent gasses as it powers away with the best power-to-weight ratio of 9.4 pounds/horsepower. Oh, in case you were wondering, a Viper RT/10 has a 7.4:1 ratio-the best we've seen this year.