The Porsche Taycan, the firm's first electric car, is in the final stages of an extensive test programme ahead of its launch later at the Frankfurt motor show – and Autocar has been given in-depth access to the development team.

Autocar was to visit a cold weather test with Porsche in northern Sweden. There was no technical briefing, no press release at what was no kind of launch but a piggyback on an extant engineering operation, but, nevertheless, after two days of conversation, the clearest picture yet of the Taycan’s technical content is now becoming apparent.

The Tesla Model S rival will be launched by Porsche in September with two power outputs, and first customer deliveries will take place before the end of the year. It seems the most powerful will now have rather more than the 600bhp originally suggested for it (perhaps as much as 630bhp), with the less powerful model around 100bhp behind. At least one more model will be introduced thereafter, likely to have an output in the mid-400bhp range.

But there's also a fourth model that has been fully engineered but may or may not go on sale. This car has a single electric motor and rear-wheel drive, so it will likely have just over 300bhp but come with a substantial weight saving. "The decision to make it is not technical but financial," a spokesperson said. "If the market wants it, we will make it." There's no two-door Taycan anywhere in the product plan, nor any ultra-sporting GT model.

The naming strategy for the car will be interesting, as Porsche is keen to make it feel as familiar as possible. So expect a conventional approach, with the range topper called the Taycan Turbo, with GTS, S and standard Taycan badging also to be used. A high-riding crossover version based on the Mission E Cross Turismo concept is planned.

Much speculation has surrounded the weight of the Taycan, but I was told it was ‘in the range of the Panamera hybrid’, which means around 2250kg, making it a touch heavier than the Jaguar I- Pace and on a par with the Tesla Model S. Acceleration for the top model is now informally referred to as ‘way below’ the 3.5sec 0-62mph sprint originally claimed for the Mission E. Interestingly, all Taycans will also be capable of at least 155mph, a function not only of their power but also the two-speed gearbox, which, like that in the BMW i8, allows prolonged use of full electric power at sustained high velocity.

Porsche has also been improving the repeatability of the Taycan’s performance. It can now do at more than a dozen 0-62mph standing starts with no fall-off in power (earlier talk was around 10) and at least four 0-124mph runs without degradation, which is doubtless at least four more than most owners will attempt. It will maintain its top speed "for longer than you could drive at that speed on any public road".