It was absolutely no part of the CARkeys plan for the Corolla test that it should involve, for almost a complete day, battling through France in the most torrential downpour experienced there for many years.On motorways which south of Lyon were themselves part-awash as they passed above flooded fields and bank-bursting rivers, and north of there to the edge of the weather system around Dole were being bombarded by rain which fell so hard it was bouncing back up off the streaming tarmac, the most appropriate Toyota might have been a Land Cruiser Amazon.Yet the much lighter and lower Corolla hatchback was never fazed by the conditions, even during momentary periods of indrawn breath by the driver on two-lane stretches of autoroute as it entered the spray zone between inner-lane trucks and outer-lane armco barriers.This was a lesson, incidentally, in the fact that some truck designs allow spray to be blasted sideways in something like a six-foot high wall, while others keep the spray noticeably lower, below overtaking-car windscreen level. And although there are limits to what can be expected, the best French anti-spray road surfaces are amazingly effective.The car was the top-rated Corolla turbo diesel, a five-door T Spirit with the uprated 114bhp two-litre D-4D engine. Altogether a fine product of two separate UK factories - Toyota's engine plant at Deeside in North Wales, and the main car assembly facility at Burnaston in Derbyshire.One major attraction of the current-generation Corolla is that it's an excellent packaging job for such a smart-looking compact car, with generous rear cabin room, and plenty of luggage space despite having a full-size spare wheel.Although there are extra-cost option packs including features like satellite navigation and traffic avoidance advice, the T Spirit is well presented and kitted-out in catalogued form, with digital air-conditioning, an electric slide/tilt sunroof, a leather-rimmed steering wheel with duplicate audio controls, a certain amount of metal-effect interior trim (lost on me, as it happens), and so on.There's a wide range of adjustments for the front seats, with the recline action taken care of by cranking up a rather ratchety lever. Long sessions at the wheel are no problem. The conventional instruments are particularly clear except when you go to lights-on for traffic reasons rather than approaching darkness, when they dim too much.Inside and out, the standard of fit and finish is impressive, and there's no doubt that the latest cars carrying a model name which has already sold nearly 30 million world-wide are closer than ever before to being top of the class against their direct rivals.Of course, the T Spirit D-4D isn't cheap. There's no bargain-basement approach to the build quality or equipment level, and the 114bhp diesel engine with its variable nozzle turbocharger and other improvements is away ahead of the 89bhp version available elsewhere in the range.With 206lb/ft of torque on tap from 2000rpm there's strong mid-range response and performance of a kind which some people on the road obviously aren't expecting from a Corolla - it's easy to shrug off other drivers' elbows-out attitude on motorways - and yet the Euro IV compliant D-4D engine also offers relaxed 80mph autoroute cruising.In this form, the Corolla simply eats up the miles, and it does so with excellent economy. Running for most of the time on inexpensive French diesel instead of the "Chancellor's Special" UK equivalent, the test car averaged over 53mpg from Calais to Nice and back. On the dry southwards run the read-out on the trip computer sometimes got down to within a point or two of 51.0mpg, but never actually reached it.Toyota hasn't quite got the emissions balance right, though. The three-door D-4D T Spirit manages 149g/km, but the five-door is on the list at 151g/km, which puts it into a higher VED band. Engine 1998cc, 4 cylinders Power 114bhp Fuel/CO2 49.6mpg / 151g/km Acceleration 0-62mph: 10.6 seconds Top speed 116mph Price £15,400 Details correct at publication date