BX update

Fourwheelsteer’s faithful if sometimes fallible Citroen BX has received some long overdue care from the good people of Preservation Garage Services (PGS) in Warwick. The same people who did such a good job of looking after my old BX performed a service and changed the cam belt and the car seems better as a result. There may be nothing measurable – it is too early to see if fuel economy has improved and I’ve not tried to measure acceleration or top speed – but the engine sounds sweeter and feels more willing.

A 1,360cc engine in a large-ish hatchback body might not seem like the perfect recipe for driving enjoyment but the BX only weighs 900kg so the 72bhp motor does not have to work too hard. The power unit is abetted in its task by a five-speed gearbox with ratios perfectly judged to make the most of the engine’s efforts. Although the overall gearing feels rather low – there is no rev counter to verify this assumption – there are no noticeable gaps between gears. The result is that there is always a gear that is right for the occasion.

Sadly, the merits of well-spaced gear ratios are being abandoned by manufacturers for the sake of fuel consumption and carbon dioxide figures. Several times this year I have read boasts of making the top three gears in a five-speed gearbox higher whilst leaving first and second alone – what can this do except leave a big gap between second and third gear? It probably fits the strictures of the standard test procedure perfectly but our roads are not standardised and on the road there will be times when the choice is stream or strain, neither of which is ideal.

This isn’t a new problem; the industry has been producing oddly geared cars for as long as it has been producing cars but it can make a big difference between enjoyment and frustration when driving. If you want a car with perfect gearing all the time surely you need some sort of continuously variable transmission.

2008 Wish list part 2

No Gears

With the end of the year rapidly approaching you can be sure that lots of retrospective views of 2007 are being readied for publication. Rather than look back (which I will do) I would rather look forward and think about some of the cars I’d like to drive in the next year.

Once upon a time I owned a Ford Granada with an old-fashioned 3-speed automatic, which worked well but could have used another ratio. At the other extreme I once borrowed a Land Rover Defender which had ten possible gear ratios by combining a 5 speed gearbox with a low-ratio transfer box. On the road such low gearing was no use but on the whole you can never have too many gears. The greater number of gears the easier it is to keep the engine working either at speeds that offer the best mix of performance and economy (or the best of either if you prefer).

There comes a point where increasing the number of fixed gear ratios becomes impractical. Some Mercedes have 7-speed autos (and they seem to work well) while Lexus have an 8-speed transmission in the LS-series but how far can this strategy go? There must come a point where either the Van-Doorne or Torotrak transmissions, with steplessly variable gear ratios between fixed limits, become a smarter choice.

The logic behind such transmissions is persuasive, the engine turns at a steady speed and the transmission adjusts the ratio as the car accelerates. Eventually the transmission finds a point of equilibrium where the power supplied by the engine is matched by the power necessary to maintain a steady speed. At anything less than top speed the transmission will adjust so that the engine is turning as slowly as possible in order to maintain a steady cruising speed. Steady speeds are not really what I am interested in; I want to know how the transmissions cope with transitions, from cruising speed to acceleration, stopping and starting. A transmission without fixed ratio steps also promises to be an interesting aural experience; it is the one thing that nearly everyone dislikes about stepless transmissions and I want to see how I feel about it.

Geared up

I was reading through this week’s Autocar, which featured a full road test of the BMW 123D coupé. Now I’m no BMW fan but the 123D looks like it has an awful lot going for it. Because I had plenty of time on my hands I studied the technical detail of the car very closely. Looking at the gear ratios I spotted something unusual; the fifth gear ratio was 1:1. It was a clear reminder and indicator that the BMW has an old-fashioned front-engine, rear-wheel drive layout. I wish there were more cars like it.