BMW’s relentless 3-series road show moves up a gear this month with the showroom debut of the fifth generation model, 30 years after the original. The bad news for rivals is that Munich continues to show no mercy.

The Mercedes-Benz C-class and Audi A4 were refreshed just in time to make Mk IV appear a little tired, but the 3-series now has the styling, sophistication and brand-power to remain Britain’s No1 premium sports saloon.

It may look a little like a scaled-down, softened 5-series but the model comes off the same platform as the 1-series. The 3-series is the best example yet of chief designer Chris Bangle’s sharper and controversial BMW restyling programme: it detracted from the 7-series, but has matured in time to re-energise the company’s biggest seller.

Visually, the 3-series offers more with its crisper, sculpted lines and it delivers all round, with improved performance, ride/handling, cabin space and driving pleasure. It is on sale with a choice of 2.0-litre, four-cylinder petrol and diesel engines, and a six-cylinder 3.0-litre petrol unit.

BMW GB sold 26,500 saloons (out of a 3-series total of 65,600) in 2003 and 24,000 in 2004 after a final quarter push that left dealers short on models in January. This year, it expects to sell 18,000 new and 4,000 former saloons, with a climb back to 24,000 in 2006.

Diesel 3-series (former and new) will account for 50-60% this year and slightly more in 2006, first full year for all diesel derivatives. The 320d will take 40-45%, and the 330d (due later this year), 5%.

The 320i will be the most popular petrol (around 35%), with the six-cylinder 330i and 325i (due next month) together contributing 10% of sales. The entry-level 318i and 318d, plus the 330d, will be on sale by the end of the year, each responsible for about 5% of sales.

The new Touring is due in the UK in autumn, but the existing coupe and cabriolet continue for up to two years.

Prices rise, and the entry-level 318 arriving later will top £20,000 but BMW is unfazed. Standard equipment on the new 3-series includes six-speed manual transmission, aircon, six airbags, on-board computer, 16-inch alloys and leather-trimmed steering wheel.

Strengths:Top-class engines and suspension, BMW badge
Weakness: Bangle lines will offend some traditionalists
Opportunity: Good enough for conquest sales
Threat: Improved rivals
USP: It’s a 3-series... enough said
Prices: £21,090 (320i) to £28,455 (330i SE)
Engines: 2.0 petrol (150bhp) and diesel (163bhp) and 3.0 six-cyl petrol (258bhp).
Transmissions: 6spd manual (6spd auto/Steptronic £1,420 option), rwd
Performance: 0-62mph 6.3-9.0 secs 137-155mph (governed) top speed
Efficiency: 33.2-49.6mpg (comb) 153 – 210g/km CO2
CAP RVs: n/a
Rivals: Mercedes C-class, Audi A4, Jaguar X-type (Lexus IS200 and Alfa 159 later)