Since we all know the MX5 is one decent handling car, I would really recommend that he considers a remapped 1.9 rather than the 2.4. Just as quick once remapped (against a non mapped 2.4) when you add in the weight difference and the way the smaller engine doesn't run out of puff so quickly up the rev range, 10 mpg better (if you're bothered, and you did put mpg on your original list), and back to my main point, it handles better. Sorry, but I did drive both before choosing mine. Otherwise I fear you'll be disappointed with the fact that the 2.4 won't be any more economical than the Mazda.
AROC Cotswold Section Treasurer
2002 156 2.0 Lusso . . .1976 Spider 2000 Veloce . . . 2009 159 JtdM Ti . . . 1985 90 2.5 V6 Gold Cloverleaf